Pressure adjustment mechanism, liquid tank, liquid providing device, ink cartridge, and inkjet printing apparatus

ABSTRACT

A pressure adjustment mechanism can provide ink to a subtank with the inside of the subtank being opened to outside air, by using a low driving force. A liquid tank holds liquid to be used by a printing apparatus. The liquid tank has a structure in which a capacity of the liquid tank can be changed so as to generate a negative pressure in the liquid tank. The liquid tank includes a case having an opening at one side of the tank, and a flexible film that covers the opening, and a compressed spring in the tank for pressing the film outwards.

TECHNICAL FIELD

The present invention relates to a pressure adjustment mechanism for aninkjet head device, and an inkjet printer that uses the pressureadjustment mechanism. Specifically, with this pressure adjustmentmechanism, a driving mechanism can use a low driving force when ink isprovided to an ink subtank provided at the inkjet head device with theinside of the subtank being open to the outside air. Specifically, theinkjet printer uses the pressure adjustment mechanism to provide ink tothe inside of the subtank while adjusting a pressure of the subtank.

The present invention also relates to a liquid tank, a liquid providingdevice, an ink cartridge, and an inkjet printer (inkjet printingapparatus).

BACKGROUND ART

FIG. 1 is a perspective view showing disassembled elements that are usedat a conventional inkjet head device of an inkjet printer. In FIG. 1,the reference number 10 designates a lever, 13 a driving mechanism fordriving the lever 10, 20 a carriage for mounting an inkjet head thereon,21 an air releasing pin, 22 a negative pressure pin, 23 an elasticmember, 30 a subtank mounted on the carriage 20 for holding ink, 31 anair releasing opening used for adjusting a pressure inside a subtankcase to be an atmospheric pressure, 32 a negative pressure lever, 40 aninkjet head (hereinbelow, referred to as a head), 50 an ink cartridge,and 51 a connection tube for connecting the ink cartridge 50 to thesubtank 30 to provide ink to the subtank 30.

In the case of an inkjet printer that includes the cartridge containinga large amount of ink, or an inkjet printer for producing high qualityimage, when the ink cartridge and the head are attached in the carriagetogether, the weight of the carriage can affect the operation the headso as to cause the image to be out of the correct position at the timethe carriage 20 works. For this reason, as shown in FIG. 1, the inkcartridge 50 is disposed external to the carriage 20, and the subtank 30that temporarily holds ink is mounted on the carriage 20.

When the inside pressure of the subtank 30 is positive, ink leaks (isexuded) from the head 40 due to the weight of the ink in the subtank 30.Accordingly, it is necessary to set the inside pressure of the subtank30 to be negative. Such pressure setting becomes important when ink isejected from the head. However, the ink can be mixed with air thatenters the subtank 30 from the ink cartridge 50 or the connection tube51. As a result, an amount of the air in the subtank 30 graduallyincreases, and thereby, the inside pressure of the subtank 30 changes soas to degrade the image formed by the ink. In order to deal with thisproblem, the ratio of the air inside the ink cartridge 50 as well as theinside pressure of the ink cartridge 50 are periodically controlled soas to become the original values.

FIG. 2 is a perspective view showing disassembled elements of thesubtank 30. The subtank 30 includes a case 33 having an approximatelyrectangular upper wall 39 a, an approximately rectangular bottom wall 39b, and three approximately rectangular side walls 39 c. The case 33 hasone open side. The subtank 30 further includes a film 34 for coveringthe one open side of the case 33, an elastic member 36 for pressing thefilm 34 from the inside of the case 33 via a plate 35, and a negativepressure lever 32 that is elastic and plate-shaped and presses the film34 towards the inside of the case 33 from the outside of the case 33.The setting is made such that the force on the film 34 exerted from theinside by the elastic member 36 is larger than the force on the film 34exerted from the outside by the negative lever 32. Accordingly, at theinitial setting, the film 34 is pressed outwards. The balanced positionof the film 34 determined by the negative pressure lever 32 and theelastic member 36 changes in accordance with the change in the insidepressure of the subtank 30 during the operation. When an amount of theink in the subtank 30 decreases, the film 34 is pressed inwards,accompanying the change (reduction) of the inside pressure.

In a normal state, an air releasing opening 31 provided on one of theside walls 39 c is sealed with an elastic member 311 such as a spring, asphere 312, an elastic member 313 such as rubber, and a cap 314 thatclosely contact with one another. Also, in a normal state, an inkproviding opening 37 provided on the upper wall 39 a of the case 33 issealed with an elastic member 371 such as a spring, a sphere 372, anelastic member 373 such as rubber, and a cap 374 that closely contactwith one another. The spheres 312 and 372 are pressed by the elasticmembers 311 and 371, respectively. The ink providing opening 37 becomesopen by the pressure of the ink that flows to the subtank 30 from thecartridge 50 via the connection tube 51 shown in FIG. 1, and thereby,the flowing ink is provided to the inside of the subtank 30. The airreleasing opening 31 becomes open when the air releasing pin 21 providedon the carriage 20 shown in FIG. 1 is pressed inwards to adjust theinside pressure of the subtank 30.

The negative pressure pin 22 of the carriage 20 presses the negativepressure lever 32 of the subtank 30 inwards from the outside. That is,the negative pressure pin 22 is pressed inwards so that the negativepressure lever 32 can be moved towards the inside of the subtank 30, andthe inside capacity of the subtank 30 can decrease. The elastic member23 is provided for forcing the negative pressure lever 32 and thenegative pressure pin 22 to be separated from each other. Therefore, ina normal state, the negative pressure lever 32 and the negative pressurepin 22 do not contact each other due to the elastic member 23.

In the operation of the inkjet head device having the above-describedstructure, the air releasing pin 21 is operated to open the airreleasing opening 31, and the negative pressure pin 22 is operated topress the negative pressure lever 32 inward so that an inside capacityof the subtank 30 can become reduced. Then, in the state in which thesubtank 30 has the reduced capacity, the subtank 30 is filled with inkvia the ink providing opening 37. The filled ink is detected by filledink detection sensors 38 disposed at the upper part of the subtank 30.Based on the result detected by the filled ink detection sensors 38,providing of the ink is controlled. In accordance with this control, thevolumes of air and ink inside the subtank 30 are determined. Then, theair releasing opening 31 is closed. In the state in which the airreleasing opening 31 is closed, the negative pressure lever 32 that isheld at the inward position is released by removing the inward pressingforce on the negative pressure lever 32. By performing such anoperation, it is possible to control the inside pressure of the subtank30 to be a constant negative pressure, and to stabilize ink ejectioncharacteristics of the head 40.

FIG. 3 is a perspective view showing an example of the structure of adriving mechanism provided at the main body side of the printer forpressing and moving the negative pressure pin 22 and the air releasingpin 21. In FIG. 3, the reference number 10 designates a lever, 11 an airreleasing pin pressing part, 12 a negative pressure pin pressing part,14 a cam, 15 a solenoid, 16 an elastic member, 17 a sensor (HP sensor),and 18 a rotational shaft. The lever 10 includes the air releasing pinpressing part 11 for pressing the air releasing pin 21, and the negativepressure pin pressing part 12 for pressing the negative pressure pin 22.The pressing phase or level at which the air releasing pin pressing part11 presses the air releasing pin 21 is different from the pressing phaseor level at which the negative pressure pin pressing part 12 presses thenegative pressure pin 22. With this difference in the pressing phase,when the lever 10 is operated, the air releasing opening 31 is made openby the air releasing opening pin 21 before the negative pressure lever32 is pressed. Furthermore, with this difference in the pressing phase,after the air releasing pin 21 is moved outwards, and the air releasingopening 31 is thereby made closed, the pressing force acting on thenegative pressure lever 32 by the negative pressure pin 22 is released.

The elastic member 16 drives the lever 10 to move in the directionopposite the direction of pressing the negative pressure pin 22 and theair releasing pin 21. The rotational shaft 18 to which the cam 14 isattached is provided for moving the lever 10 so as to perform thepressing operation of the negative pressure pin 22 and the air releasingpin 21. Accompanying the rotation of the rotational shaft 18, the cam 14acts on the lever 10 so as to move (rotate) the lever 10. The solenoid15 having a flapper is provided for rotating the rotational shaft 18. Afiller provided on the rotational shaft 18 releases/shields the sensor17 so that the sensor 17 can detect a home position (HP) of therotational shaft 18.

The above-described ink filling operation in which the subtank 30 isfilled with ink by pressing the negative pressure pin 22 and the airreleasing pin 21 is referred to as an air releasing filling operation.In the air releasing filling operation, it is possible to keep apressure in the subtank 30, an amount of the ink in the subtank 30, andan amount of the air in the subtank 20 at desired values. On the otherhand, an ink filling operation in which only ink is provided to thesubtank 30 without pressing the negative pressure pin 22 and the airreleasing pin 21 is referred to as a normal filling operation. In thenormal filling operation, the air amount in the subtank 30 that hasgradually increased is not controlled, so that the inside pressure ofthe subtank 30 is shifted from a desired value.

FIG. 4 is a partial schematic illustration for a lever operationmechanism provided at the main body of the printer. In theabove-described structure, in order to press and move the negativepressure pin 22 and the air releasing pin 21, it is necessary to apply aforce to the lever 10 that is larger than the reaction force by thenegative pressure pin 22 and the air releasing pin 21. As shown in FIG.4, in the conventional structure of the cam 14, the lever 10 is rotatedcounterclockwise by the cam 14, the cam 14 being rotated clockwise bythe rotational shaft 18. Accordingly, the reaction force R1 by the lever10 acts on the rotational shaft 18 to apply a rotational force R2 thatdrives the cam 14 to rotate in the direction opposite the desiredoperation direction. For this reason, in order to rotate the cam 14 tomove the lever 10, a motor or a solenoid that has a high driving forceis conventionally used as a driving mechanism at the main body of theprinter for operating the lever 10.

However, the air releasing filling operation needs to be performed onlywhen the air amount inside the subtank 30 increases, and in reality, thenecessary frequency of the air releasing filling operation is muchsmaller than that of the normal filling operation. Accordingly, in termsof the manufacturing costs of the printer, it is not wise to use theexpensive motor or solenoid for the air releasing filling operationhaving the less necessary frequency.

FIGS. 5A, 5B, and 5C are illustrations for the lever operation at thecarriage on which plural-color subtanks are mounted. The order of thelever operation procedure is from FIG. 5A to FIG. 5C. In FIGS. 5Athrough 5C, the subtanks (not shown) that correspond to a plurality ofcolors (in this example, four colors) are provided on the carriage 20.In the drawings, air releasing pins 21 a through 21 d, and negativepressure pins 22 a through 22 d that correspond to the respectivesubtanks extend from the carriage 20. For example, in the case of tyingto press the air releasing pin 21 a and the negative pressure pin 22 alocated at the most left side of the carriage 20 when seen from the pinside to perform the air releasing filling operation, the air releasingpins 21 b through 21 d and the negative pressure pins 22 b through 22 dof the other subtanks corresponding to the pins 21 b through 21 d andpins 22 b through 22 d are also successively pressed by the lever 10,accompanying the movement of the carriage 20. When these affected othersubtanks are not filled with the ink, the air amounts in the subtanksbecome larger than in the case where the appropriate air releasingfilling operation is performed. Furthermore, in this case, the insidepressures of the suntanks cannot be controlled to be a desired value.

Furthermore, in the related art, generally, an inkjet printing apparatusis applied to an image printing apparatus or an image forming apparatussuch as a printer, a facsimile machine, a copying machine, and aplotter. A printing head of the inkjet printing apparatus includes anozzle for ejecting ink, a ejection room (a pressure room, a pressurizedliquid room, or an ink passage) that communicates with the nozzle, andenergy generation means for generating energy that is used forpressurizing the ink in the ejection room. When an image is recorded onpaper by a serial printer, a carriage is moved in a main runningdirection, paper is fed in a sub-running direction, and the ink isejected from the printing head. Instead of paper, any medium on whichthe ink will adhere may be used.

In such a serial inkjet printing apparatus, ink needs to be provided tothe printing head mounted on the carriage. Generally, the printing headand an ink cartridge (or an ink tank) that provides ink are disposedtogether on the carriage. The ink cartridge integrally formed with theprinting head may be disposed on the carriage.

An appropriate ink meniscus needs to be formed at the nozzle hole of thehead when such an ink cartridge is used. Furthermore, it is necessary toprevent bubbles or foam from being formed. In addition, when the head isdisposed so as to, be oriented in the downward direction, the ink needsto be prevented from dropping and leaking from the nozzle. For thesereasons, the ink pressure needs to be negative. Accordingly, an inkjetprinting apparatus that has a porous ink absorption body for absorbingthe ink and that generates a negative pressure is widely used.

In another usage example, a subtank having a small capacity is disposedon the carriage, and a main cartridge having a large capacity isdisposed at the main body side of the printer. In this arrangement, theink is supplied to the subtank from the main cartridge disposed at themain body side.

In the case where the only ink cartridge is disposed on the carriagewithout using the main cartridge at the main body side, the inkcartridge needs to be replaced with new one when the ink cartridge runsout of the ink. Accordingly, when the ink is frequently used for highspeed printing or high quality image printing, the cartridge needs to bereplaced more frequently. On the other hand, when the capacity of theink cartridge is made large, the weight of the entire carriage becomeslarge. Accordingly, it becomes difficult to move the carriage at a highspeed, and further, the size of the carriage and the like becomes large.In addition to that, the output energy of the motor for driving thecarriage needs to be large. Moreover, the weight of the carriage changessignificantly, so that the movement characteristics of the carriagechange during the printing operation, and it becomes difficult tomaintain stable printing accuracy.

According to Japanese Laid-Open Patent Application Nos. 10-128992 and10-235892, a subtank having a small capacity is disposed on thecarriage, and the main cartridge having a large capacity is disposed atthe main body side of the printer. The subtank is connected to the maincartridge by a tube. With this structure, when the ink in the subtankdecreases, the ink is supplied to the subtank from the main cartridge.Further, according to Japanese Patent No. 3053017, two tubes, i.e., anink providing tube and an air sucking tube are connected to the suntank.

In the above-described ink cartridge, the ink in the cartridge is suckedvia the nozzle so that the negative pressure can be generated. Thegenerated negative pressure is maintained by the porous body. However,the ink is wasted without being used, and the absorbing body for holdingthe waste ink in the printer becomes larger. In addition, using the onlyink cartridge disposed on the carriage causes the ink shortage moreoften.

In the case of the printer disclosed in the above Japanese Laid-OpenPatent Application Nos. 10-128992 and 10-235892, since the tube haspermeability of air and moisture, the air enters the inside of the tube.Also when the ink supply unit is attached or detached, the air entersthe inside of the tube. Since the disclosed printers do not have afunction of discharging the air mixed with the ink inside the ink supplypassage (the tube), a large amount of air enters the subtank when thetube is used for a long time, resulting in printing being degraded.

Furthermore, in the printer disclosed in the above Japanese Patent No.3053017, the ink is provided to the subtank while the air is dischargedfrom the subtank. Accordingly, the air is not accumulated in thesubtank. However, in this printer, it is necessary to connect two tubes,that is, the ink providing tube and the air sucking tube to the subtank.Particularly, in the case of the color inkjet printing apparatus, eighttubes need to be connected to respective subtanks corresponding to fourcolors.

In this case, the subtanks are moved with the subtank being disposed onthe carriage, the tubes connected to the subtanks need to have lengthsthat are at least equal to the length of the movement of the subtanks.Accordingly, it is necessary to arrange the plural long tubes in theprinter, and to provide a special pump for generating the negativepressure, resulting in high manufacturing costs.

DISCLOSURE OF THE INVENTION

It is a general object of the present invention to provide a pressureadjustment mechanism that enables a relatively low driving force usedfor operation of a subtank that holds ink, and an inkjet printer thatuses this pressure adjustment mechanism.

It is another object of the present invention to provide a liquid tankin which a negative pressure in the liquid tank can be adjusted withoutincreasing waste ink, with a simple structure.

It is another object of the present invention to provide a liquidproviding device that can reliably provide liquid to a printing head orthe like for a long time.

It is another object of the present invention to provide an inkjetprinting apparatus that can perform stable printing for a long time.

It is another object of the present invention to provide an inkcartridge having a simple structure in which the ink cartridge isintegrally formed on a head such as a printing head, and a negativepressure in the ink cartridge can be adjusted without increasing theamount of waste ink.

According to a first aspect of the present invention, there is provideda pressure adjustment mechanism for an inkjet head device, comprising: ahead that ejects ink; a carriage that mounts the head thereon and moves;a subtank that is mounted on the carriage, temporarily holds inkprovided from a cartridge, and provides the temporarily held ink to thehead; a lever that is moved to adjust a pressure inside the subtank; anddriving means for moving the lever selectively to a first position ofthe lever or a second position of the lever. Specifically, in thispressure adjustment mechanism, the subtank includes pressure adjustmentmeans that have air releasing control means and negative pressurecontrol means, the air releasing control means are provided on a sidewall of the subtank, enabling an inside of the subtank to be opened tooutside air, and enabling the inside of the subtank to be closed fromoutside air, and the negative pressure control means generate a negativepressure inside the subtank. Further, in this pressure adjustmentmechanism, the lever acts on the pressure adjustment means at the firstposition of the lever when the carriage is at a second position of thecarriage, and the acting on the pressure adjustment means by the leveris released at the second position of the lever. Furthermore, in thispressure adjustment mechanism, the driving means includes a cam thatacts on the lever so as to move the lever, and means for rotating thecam. In addition, in this pressure adjustment mechanism, when thecarriage is at a first position of the carriage where the lever does notact on the pressure adjustment means even if the lever is moved to thefirst position of the lever, the lever is moved by the driving means tothe first position of the lever, and the carriage is moved to the secondposition of the carriage with the lever being at the first position ofthe lever to perform air releasing control for the subtank and negativepressure control for the subtank.

With this pressure adjustment mechanism, it is possible to realize arelatively low driving force of the driving means, and to manufacturethe driving means at a low cost.

According to a second aspect of the present invention, the pressureadjustment mechanism of the first aspect further comprises: a pluralityof subtanks that are mounted on the carriage, have a substantially samestructure as that of said subtank and hold ink whose types are differentfrom each other; a plurality of levers that have a substantially samestructure as that of said lever; and a plurality of pressure adjustmentmeans that are respectively provided on the plurality of subtanks, andhave a substantially same structure as that of said pressure adjustmentmeans, wherein each of the plurality of pressure adjustment meansreceives action applied by one of the plurality of levers (or each ofthe plurality of pressure adjustment means are activated by one of theplurality of levers).

With this pressure adjustment mechanism, it is possible to perform thenegative pressure control of the subtanks independently of each other.Furthermore, the time required for providing ink to the subtanks withthe insides of the subtanks being open to outside air can be reduced. Inaddition, it is possible to keep a stable inside pressure of eachsubtank.

According to a third aspect of the present invention, in the pressureadjustment mechanism of the first aspect or the second aspect, thepressure adjustment means include an air releasing pin that enables anair releasing opening formed on the subtank to be opened and closed soas to perform the air releasing control, the negative pressure meansinclude a negative pressure pin that moves a part of a wall constitutingthe subtank so as to control a pressure inside the subtank to be adesired negative pressure, the lever presses the air releasing pin andthe negative pressure pin at the first position of the lever when thecarriage is at the second position of the carriage, and the lever isseparated from the air releasing pin and the negative pressure pin atthe second position of the lever, and the air releasing pin is separatedfrom the negative pressure pin in a vertical direction.

With this pressure adjustment mechanism, it is possible to perform thepressure control of the subtank at a predetermined procedure or timingwhen ink is provided to the subtank with the inside of the subtank beingopen to outside air.

According to a fourth aspect of the present invention, in the pressureadjustment mechanism of any one of the first aspect to the third aspect,when the lever acts on the pressure adjustment means, and receives areaction force that is generated from the pressure adjustment means andthat causes a stress acting on the lever in a direction of releasing theacting by the lever on the pressure adjustment means, the stressreceived by the lever acts on the cam towards a center axis of arotational shaft of the cam so as to restrain movement of the levercaused by the stress.

With this pressure adjustment mechanism, it is possible to use thedriving mechanism that generates low torque.

According to a fifth aspect of the present invention, in the pressureadjustment mechanism of any one of the second aspect to the fourthaspect, when a series of movements of one of the plurality of leverssuccessively or simultaneously causes some of the plurality of pressureadjustment means to function, ink is provided to some of the pluralityof subtanks corresponding to the some of the plurality of pressureadjustment means.

With this pressure adjustment mechanism, when ink is provided to aplurality of subtanks, the inside pressures of the subtanks can beprevented from changing. In other words, in the case where ink isprovided to a plurality of subtanks of plural colors, it is possible toprevent the inside pressures of the plurality of subtanks from changing,by providing ink to the plurality of subtanks with the insides of theplurality of subtanks being open to outside air.

According to a sixth aspect of the present invention, there is providedan inkjet printer comprising the pressure adjustment mechanism describedin any one of the first aspect to the fifth aspect. This inkjet printerprovides ink to an inside of the subtank or insides of the subtankswhile the inkjet printer uses the pressure adjustment mechanism so as toadjust a pressure in the subtank or pressures in the subtanks.

According to a seventh aspect of the present invention, there isprovided a liquid tank having a structure in which a capacity of theliquid tank can be changed so as to generate a negative pressure in theliquid tank.

Preferably, this liquid tank includes an air releasing opening that canbe opened and closed so as to open and close the inside of the liquidtank to outside air. A negative pressure can be generated by opening andclosing the air releasing opening, and changing the capacity of theliquid tank. Preferably, the liquid tank includes an air releasing valvethat is provided at the air releasing opening and can keep the airreleasing opening closed from outside air, by using a spring member.

Preferably, the liquid tank includes a liquid providing opening used forproviding liquid to the inside of the liquid tank from outside theliquid tank. Preferably, a position of the liquid providing opening islower than a position of the air releasing opening. Preferably, theliquid tank includes reverse flow prevention means for preventing liquidfrom flowing in reverse via the liquid providing opening from the insideto the outside of the liquid tank. The reverse flow prevention means maybe valve means, or a fluid resistance part that produces large fluidresistance. Further, a valve that is opened and closed in accordancewith a pressure inside the liquid tank may be provided at the liquidproviding opening. In addition, liquid providing to the liquid tank maybe stopped after the liquid providing opening is filled with the liquid.

Furthermore, the liquid tank preferably includes pressing means forpressing the liquid tank from outside the liquid tank. Preferably, theliquid tank includes a displacement member that moves in accordance withchange in a capacity or a volume of the liquid tank. Preferably, anamount of movement of the displacement member is larger than an amountof deformation of the liquid tank that indicates change of the capacityof the liquid tank. The displacement member may cause the capacity ofthe liquid tank to be changed. Further, the displacement member may bemade of a material having high thermal conductivity. Further, liquidproviding to the liquid tank may be controlled based on a position ofthe displacement member.

Preferably, at least two detection electrodes are provided at an upperpart of the inside of the liquid tank, and extend to respectivedifferent depths in the liquid tank. Preferably, the liquid tankincludes an air extraction space that communicates with the airreleasing opening, and one of the detection electrodes is provided atthe air extraction space.

In addition, a spring member for generating a negative pressure may beprovided inside the liquid tank, and a spring member for maintaining anegative pressure may be provided inside the liquid tank. The inside ofthe liquid tank may be divided into two rooms so that different kinds ofliquid can be held in the respective rooms.

According to an eighth aspect of the present invention, there isprovided a liquid providing device having any one of the above-describedliquid tanks. The liquid providing device may include liquid providingmeans for providing liquid to the liquid tank by using a difference in apressure head. Preferably, the liquid providing device includes adriving member that is disposed on a member for fixing the liquid tankand moves so as to change a capacity of the liquid tank. Preferably, theliquid providing device includes restriction means for restricting anamount of the movement of the driving member. Further, a gap preferablyexists between the driving member and the liquid tank, and the liquidproviding device includes a spring member for maintaining the gap.

According to a ninth aspect of the present invention, there is provideda liquid providing device that includes a liquid tank having an airreleasing opening, and liquid providing means for providing liquid tothe liquid tank by selecting either a state where the inside of theliquid tank is opened to outside air, or a state where the inside of theliquid tank is closed from outside air.

According to a tenth aspect of the present invention, there is provideda liquid tank that includes an air releasing opening, andopening/closing means for opening the air releasing opening inaccordance with a surrounding temperature.

According to an eleventh aspect of the present invention, there isprovided a liquid providing device that includes a liquid tank having anair releasing opening, and an opening/closing driving member that isprovided on a member for fixing the liquid tank and moves so as to openand close the air releasing opening. Preferably, the liquid providingdevice includes restriction means for restricting the movement of theopening/closing driving member. Further, a gap preferably exists betweenthe opening/closing driving member and the liquid tank. In addition, theliquid providing device preferably includes a spring member formaintaining this gap.

According to a twelfth aspect of the present invention, there isprovided an inkjet printing apparatus that includes any one of theabove-described liquid tanks (ink tanks), or any one of theabove-described liquid providing devices (ink providing devices).Preferably, the inkjet printing apparatus includes means for wiping anozzle surface of an inkjet head before the negative pressure isgenerated in the liquid tank.

According to a thirteenth aspect of the present invention, there isprovided an ink cartridge that includes an inkjet head for ejecting ink,and any one of the above-described liquid tanks that is integrallyformed on the inkjet head.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective structural view of disassembled elementsprovided at an inkjet head device of an inkjet printer in the relatedart.

FIG. 2 is a detailed perspective view of a disassembled subtank shown inFIG. 1.

FIG. 3 is a perspective view of a driving mechanism for pressing andmoving a negative pressure pin and an air releasing pin in the relatedart.

FIG. 4 is a partial schematic view showing an operation mechanism of thedriving mechanism shown in FIG. 3.

FIGS. 5A through 5C show a lever operation at a carriage on whichsubtanks corresponding to a plurality of colors are mounted in therelated art.

FIG. 6 is a perspective view showing disassembled elements of a part ofan inkjet printer according to the present invention.

FIG. 7 shows a driving mechanism of a driving unit shown in FIG. 6.

FIGS. 8A through 8H are partial schematic view of an operation of thedriving unit and a carriage shown in FIG. 6.

FIG. 9 shows the engagement between a cam and a lever shown in FIG. 7.

FIG. 10 is a perspective view of an example of the inkjet printeraccording to the present invention.

FIG. 11 shows the basic structure of an ink tank according to a secondembodiment of the present invention.

FIG. 12 shows the operation of the ink tank shown in FIG. 11.

FIG. 13 shows an ink providing device including an ink tank according toa third embodiment of the present invention.

FIG. 14 shows the operation of the ink providing device shown in FIG.13.

FIG. 15 shows the basic structure of an ink providing device includingan ink tank according to a fourth embodiment of the present invention.

FIG. 16 shows the operation of the ink providing device shown in FIG.15.

FIG. 17 shows the basic structure of an ink providing device accordingto a fifth embodiment of the present invention.

FIG. 18 is a plan view showing the important part of the ink providingdevice shown in FIG. 17.

FIG. 19 shows the operation of the ink providing device shown in FIG.17.

FIG. 20 shows the basic structure of an ink providing device includingan ink tank according to a sixth embodiment of the present invention.

FIG. 21 is a plan view showing the important part of the ink providingdevice shown in FIG. 20.

FIG. 22 is a side view showing the important part of the ink providingdevice shown in FIG. 20.

FIG. 23 shows the basic structure of an ink providing device includingan ink tank according to a seventh embodiment of the present invention.

FIG. 24A and 24B are enlarged views showing one example of a reverseflow prevention valve of the ink providing device shown in FIG. 23.

FIG. 25A and 25B are enlarged views showing another example of a reverseflow prevention valve of the ink providing device shown in FIG. 23.

FIG. 26 shows the basic structure of an ink providing device includingan ink tank according to an eighth embodiment of the present invention.

FIG. 27 shows the basic structure of an ink providing device includingan ink tank according to a ninth embodiment of the present invention.

FIG. 28 is an enlarged view showing the important part of the inkproviding device shown in FIG. 27.

FIG. 29 shows the basic structure of an ink providing device includingan ink tank according to a tenth embodiment of the present invention.

FIG. 30 shows the basic structure of an ink providing device includingan ink tank according to an eleventh embodiment of the presentinvention.

FIG. 31 shows the basic structure of an ink providing device includingan ink tank according to a twelfth embodiment of the present invention.

FIG. 32A and 32B are enlarged views showing the important part of theink providing device shown in FIG. 31.

FIG. 33 shows the basic structure of an ink providing device includingan ink tank according to a thirteenth embodiment of the presentinvention.

FIG. 34 is an enlarged view showing the important part of the inkproving device shown in FIG. 33.

FIG. 35 is a side view showing the basic structure of an ink providingdevice including an ink tank according to a fourteenth embodiment of thepresent invention.

FIG. 36 is an elevation view of the FIG. 35.

FIG. 37 is a plan view showing the basic structure of an ink providingdevice including an ink tank according to a fifteenth embodiment of thepresent invention.

FIG. 38 is an elevation view of FIG. 37.

FIG. 39 is a perspective view showing one example of an inkjet printingapparatus according to the present invention.

FIG. 40 is a plan view showing the important part of the inkjet printingapparatus shown in FIG. 39.

FIG. 41 is a partial sectional view showing an ink tank and an inkproviding device of the inkjet printing apparatus shown in FIG. 39.

FIG. 42 is a sectional plan view showing the ink tank shown in FIG. 41.

FIG. 43 is a sectional side view showing the ink tank shown in FIG. 41.

FIG. 44 is a block diagram of a control unit of the inkjet printingapparatus shown in FIG. 39.

FIG. 45 is a flow chart of an initial ink providing operation performedby the control unit of FIG. 44.

FIG. 46 is a flow chart of an ink supply control performed by thecontrol unit of FIG. 44.

FIG. 47 is a partial sectional view showing an ink tank and an inkproviding device according to a specific embodiment of the presentinvention.

FIG. 48 is a sectional plan view showing the ink tank shown in FIG. 47.

FIG. 49 is a sectional side view showing the ink tank shown in FIG. 47.

BEST MODE FOR CARRYING OUT THE INVENTION

First, a first embodiment of the present invention will be describedwith reference FIGS. 6 through 10. In the following description of thefirst embodiment of the present invention, a pressure adjustmentmechanism for adjusting a pressure inside a subtank that holds ink, andan inkjet printer using this pressure adjustment mechanism are describedin detail.

FIG. 6 is a partial perspective view showing disassembled elements in aninkjet printer according to the present invention. In FIG. 6, thereference numbers 10 a and 10 b designate a first lever and a secondlever, respectively, 11 a and 11 b air opening releasing pin pressingparts of the first and second levers 10 a and 10 b, respectively, 12 aand 12 b negative pressure pin pressing parts of the first and secondlevers 10 a and 10 b, respectively, 13 a driving unit, 21 a an airreleasing pin, 22 a a negative pressure pin, 23 a an elastic member, 301and 302 subtank units, 31 a through 31 d air releasing openings, and 32a through 32 d negative pressure levers. The air releasing pins 21 athrough 21 d and negative pressure pins 22 a through 22 d correspond torespective colors, but only the air releasing pin 21 a, the negativepressure pin 22 a, and the elastic member 23 a corresponding to thefirst color are shown in FIG. 6, and the other corresponding elementsfor other colors are not shown in FIG. 6.

In this embodiment, the inkjet printer includes the driving unit 13having two driving mechanisms each of which is similar to the mechanismusing the lever 10 described above and shown in FIGS. 1 through 5C. Eachof the subtank units 301 and 302 has two subtanks. Each color can beheld by one of the subtanks. The air releasing openings 31 a and 31 b,and the negative pressure levers 32 a and 32 b are provided on thesubtank unit 301, and the air releasing opening 31 b and 31 c, and thenegative pressure levers 32 c and 32 d are provided on the subtank unit302. As shown in FIG. 6, the driving unit 13 has two levers 10 a and 10b. As for the first color, the air releasing pin 21 a and the negativepressure pin 22 a are separate from each other in the verticaldirection. Also as for the other colors, the air releasing pin and thenegative pressure pin are separate from each other in the verticaldirection in the same manner as the pins 21 a and 22 a. Furthermore, inthis example, the air releasing pin 21 a of the first color and the airreleasing pin 21 c of the third color are in alignment with each otherin the horizontal direction. Similarly, in this example, the airreleasing pin 21 b of the second color and the air releasing pin 21 d ofthe fourth color are aligned with each other in the horizontaldirection, the negative pressure pin 22 a of the first color and thenegative pressure pin 22 c of the third color are aligned with eachother in the horizontal direction, and the negative pressure pin 22 b ofthe second color and the negative pressure pin 22 d of the fourth colorare aligned with each other in the horizontal direction. The airreleasing pins 21 a and 21 b are separated from each other with respectto the vertical direction, and the negative pressure pins 22 a and 22 bare separated from each other with respect to the vertical direction.

With this structure, the first lever 10 a at the upper side can pressonly the air releasing pins 21 a and 21 c, and the negative pressurepins 22 a and 22 c corresponding to the first and third colors, and thesecond lever 10 b at the lower side can press only the air releasingpins 21 b and 21 d, and the negative pressure pins 22 b and 22 dcorresponding to the second and fourth colors. In this example, thedriving unit 13 has two levers 10 a and 10 b, but may have four leversfor pressing respective air releasing pins and negative pressure pins offour subtanks that correspond to four colors of ink. Since when four ormore levers are provided on the driving unit 13, a size in the verticaldirection becomes larger, an appropriate plurality of levers may beprovided on the driving unit 13 in accordance with the size restriction.

FIG. 7 is an illustration of the structure of the driving unit 13 shownin FIG. 6. Elements shown in FIG. 7 correspond to the elements of thelever driving mechanism shown in FIGS. 8A through 8H. In FIG. 7, thereference number 18 designates a rotational shaft, 14 a and 14 b camscorresponding to the levers 10 a and 10 b respectively, 15 a DCsolenoid, 16 a and 16 b elastic members for driving the levers 10 a and10 b respectively, and 17 a sensor (HP sensor). In this embodiment ofthe present invention, the DC solenoid is operated so that therotational shaft 18 can be rotated to cause the cams 14 a and 14 b tomove the levers 10 a and 10 b, respectively. In this manner, thepressing/releasing operation is performed on the air releasing pins 21 athrough 21 d, and the negative pressure pins 22 a through 22 d.

FIGS. 8A through 8H are illustrations for the operation of the drivingunit for the inkjet head, and the operation of the carriage 20. Theoperation order is from FIG. 8A to FIG. 8H. As described above, each ofthe levers 10 a and 10 b moves between the position where each of thelevers 10 a and 10 b presses the air releasing pins and the negativepressure pins by the working of the cam and the position where each ofthe levers 10 a and 10 b is separate from the air releasing pins and thenegative pressure pins. Hereinbelow, the position where each of thelevers 10 a and 10 b presses the air releasing pins and the negativepressure pins is referred to as the pin pressing position, and theposition where the pressing forces on the air releasing pins and thenegative pressure pins are released is referred to as the pressurereleasing position. In this example, the two subtanks that eachaccommodate different colors of ink are attached to the carriage 20, andthe first color to the fourth color correspond to the air releasing pin21 a to the air releasing pin 21 d, respectively.

First, as shown in FIG. 8A, the carriage 20 is positioned at the suctionposition where the ink suction/filling operation can be carried out, andthe levers 10 a and 10 b of the driving unit are positioned at thepressure releasing position. At this time, the sensor 17 confirms thatthe levers 10 a and 10 b are positioned at the home positions. Next, thecarriage 20 is moved by 10.5 mm in the right direction when seen fromthe lever side in FIG. 8A. This moved position of the carriage 20 shownin FIG. 8B is referred to as the first carriage waiting position.

Subsequently, at the first carriage waiting position, the first lever 10a is operated so as to be set at the pin pressing position, as shown inFIG. 8C. In this state, the carriage 20 is moved to the suction positionwhere the lever 10 a can push the pins 21 a and 22 a. Since the firstlever 10 a is set at the pin pressing position, the air releasing pin 21a and the negative pressure pin 22 a of the first color are pressed bythe first lever 10 a, accompanying the movement of the carriage 20, asshown in FIG. 8D.

In this example, the sum of the reaction forces of the pins 21 a and 22a is 300 gf, but the attraction force of the solenoid may be 20 gf. Inother words, if at the suction position, the lever 10 a is rotated topress the pins 21 a and 22 a, the lever 10 a cannot push the pins 21 aand 21 b when the driving force of the solenoid is weak. However,according to the embodiment of the present invention, at the positionwhere the lever 21 a cannot push the pins 21 a and 22 a, the lever 21 ais set at the pin pressing position before pushing the pins 21 a and 22a, and in this state, the carriage 20 is moved to the suction position.In this manner, the structure can be made such that the reaction forcesof the pins 21 a and 22 a act towards the center of the rotational shaft18 via the lever 10 a. Accordingly, the rotational shaft 18 can receivethe reaction forces of the pins 21 a and 22 a. With this pushing mannerand the structure, the lever 10 a is not moved back to the pressurereleasing position, and a stable operation can be carried out.

When the carriage 20 is further moved to the left side when seen fromthe pin side, the pins 21 a and 22 a are released from the protrudingparts of the lever 10 a, and the pins 21 a and 22 a are not beingpressed by the lever 10 a, as shown in FIG. 8E. In this example of FIG.6 in which the driving unit 13 has two levers 10 a and 10 b, when theair releasing filling operation is performed on the pins of the firstcolor, the pins of the second color arranged next to the pins of thefirst color are not affected, i.e., not pushed, but the air releasingpin 21 c and the negative pressure pin 22 c of the third color arepushed by the first lever 10 a, accompanying the movement of thecarriage 20 because the pins are arranged as shown in FIG. 6.

When the carriage 20 is further moved from the position shown in FIG. 8Eto a second carriage waiting position shown in FIG. 8F, the pins 21 cand 22 c are released from protruding parts (the air releasing pinpressing part and the negative pressure pressing part) of the firstlever 10 a, and the pins 21 c and 22 c are not being pressed by thefirst lever 10 a. In this state shown in FIG. 8F, the solenoid isoperated so that the first lever 10 a can be rotated back to thepressure releasing position without being affected by the reactionforces of the pins 21 c and 22 c.

Meanwhile, when the air releasing filling operation is carried out onthe second and fourth colors, the second lever 10 b is operated. Inother words, at the second carriage waiting position shown in FIG. 8F,the second lever 10 b is operated to be set at the pin pressingposition, as shown in FIG. 8G. Thereafter, the carriage 20 is moved tothe right side in FIG. 8G so that the air releasing pin 21 d and thenegative pressure pin 22 d of the fourth color, and the air releasingpin 21 b and the negative pressure pin 22 b of the second color aresuccessively pushed by the second lever 10 b (this operation is notshown). In this manner, the air releasing filling operation is carriedout. Then, while the carriage 20 is made to be positioned where thereaction forces of pins do not affect the second lever 10 b, the secondlever 10 b is rotated back to the pressure releasing position, as shownin FIG. 8H, for example.

In this lever operation, when the first and second levers 10 a and 10 bare rotated, the loads from the air releasing pins 21 a through 21 d andthe negative pressure pins 22 a through 22 d are not applied to thefirst and second levers 10 a and 10 b. As described above, if the forcesfrom the pins 21 a through 21 d and the pins 22 a through 22 d areapplied to the levers 10 a and 10 b, these forces work against therotation of the cam, and increase the load on the solenoid.

According to this embodiment, as shown in FIG. 9, the shapes of the cams14 a and 14 b, and the engaging state between each cam and each of thelevers 10 a and 10 b are optimized so that even when the reaction forcesby the pins act on the levers 10 a and 10 b, the reaction forces of thepins can act on the rotational shaft 19 toward the rotational center ofthe rotational shaft 18. In this manner, the reaction forces of the pinsdo not function as the rotational force of the rotational shaft 18.Accordingly, it is not necessary to provide a mechanism for preventingthe rotation of the cam caused by the reaction forces, resulting in lowmanufacturing costs of the lever driving unit.

In the above-described embodiment, even when the air releasing fillingoperation needs to be performed for the only one color in the subtank,for example, at the time of exchanging the cartridge, the air releasingfilling operation is performed on all the colors of the subtanks. Forexample, in this embodiment, when the subtank corresponding to the firstcolor needs to be filled with the ink, the inside pressure of thesubtank corresponding to the third color is also affected by theoperation of the first lever 10 a, and is temporarily changed. However,the air releasing filling operation is also performed on the subtankcorresponding to the third color so that the inside pressure of thesubtank corresponding to the third color can be maintained at a desiredvalue.

In addition, according to the present invention, the lever may beprovided for each subtank. With this structure, when the air releasingfilling operation is performed on one subtank corresponding to onecolor, the inside pressures of the subtanks corresponding to the othercolors are not affected.

FIG. 10 is a perspective view showing one example of the inkjet printeraccording to the present invention. In FIG. 10, the reference number 40designates the inkjet printer, 41 an inkjet head device, 42 a carriagefor mounting the inkjet head device 41 thereon and moving the carriagein the directions indicated by the arrows in this figure, and 43 a rodfor supporting the carriage 42 such that the carriage can move axiallyalong the rod. The inkjet printer 40 may be structured such that thepressure adjusting mechanism as described above can be applied to theinkjet head device 41. With this structure, it is possible to realize aninkjet printer having the driving mechanism for performing the airreleasing filling operation that can be structured at a low cost.

A second embodiment of the present invention will be described withreference to FIGS. 11 and 12. In FIG. 11, the basic structure of an inktank is shown, and in FIG. 12, the operation of the ink tank is shown.The ink tank 101 includes a case 102, and a flexible film 103. The case102 is made of resin or the like, and has an opening at the one sidethereof. The flexible film 103 closes the opening of the case 102. Acompressed spring 104 for pressing the film 103 outwards is providedinside the case 102. An ink providing opening (or ink providing hole)105 for providing ink to the ink tank 101, and an ink supply opening (orink supply hole) 106 for supplying the ink to an inkjet head 120 that isa printing head are formed on the case 102.

The ink tank 101 and the inkjet head 120 may be separately provided suchthat the only ink tank can be replaced. Alternatively, an ink cartridgemay be configured so as to include the ink tank 101 and the inkjet head120 that are integrally united.

A restriction member 121 is provided at the outside of the film 103 soas to move relative to the film 103. The procedure of providing ink tothe ink tank 101 is as follows. When the ink tank 101 is to be filledwith the ink, this restriction member 121 is advanced so as to press andmove the film 103 against the force of the compressed spring 104 so thatthe capacity of the ink tank 101 can be made smaller than the capacityin the normal state. An ink tube 124 is connected to the ink providingopening 105 from an ink providing source 122 such as a main ink tank viaa valve 123.

In this state, the valve 123 is made to open so that the ink can beprovided to the inside of the ink tank 101 from the ink providing source122. At this time, the air inside the ink tank 101 is pushed anddischarged to the outside of the ink tank 101 via the ink supply opening106 and a nozzle of the inkjet head 120. After the required ink isprovided to the ink tank 101, the valve 123 is closed so as to shut thecommunication between the ink tank 101 and the ink providing source 122.

Next, the nozzle face of the inkjet head 120 is temporarily closed, andthe restriction member 121 is moved back so as to be separated from theink tank 101, as shown in FIG. 12. Since the restriction member 121 isseparated from the ink tank 101, the compressed spring 104 tries torestore the original shape to press the film 103 outwards. Accordingly,the capacity of the ink tank 101 becomes larger, and a negative pressureis thereby generated inside the ink tank 101 in accordance with thespring force.

According to this embodiment, the ink tank 101 is configured such thatthe capacity of the ink tank 101 can change. By using the capacitychange of the ink tank 101, it is possible to generate the negativepressure in the ink tank 101. In this example, the negative pressure canbe controlled by the compressed degree of the spring, so that it ispossible to easily generate and maintain the appropriate negativepressure.

Next, a third embodiment of the present invention will be described withreference to FIGS. 13 and 14. The basic structure of an ink tank 101 ofan ink providing device of the third embodiment is shown in FIG. 13, andthe operation of the ink providing device is shown in FIG. 14. In thisembodiment, an air releasing opening 107 for opening the inside of theink tank 101 to the outside is formed on the ink tank 101. An airreleasing valve 108 for opening and closing the air releasing opening107 is provided at the air releasing opening 107.

The ink providing device supplies the ink to the ink tank 101 inaccordance with operating necessity. The ink providing device includesthe ink tank 101 and pressing means 131. The pressing means includes aplunger 131 a that moves forwards to press a flexible film 103 againstthe spring force of a compressed spring 104 and that moves backwards torelease the pressure on the film 103. The pressing means 131 that aredriving means may include a driving element such as a solenoid actuator,or may be operated via a link mechanism or the like.

The ink providing device includes a main cartridge 132 that is inksupply means that accommodate a large amount of ink. The main cartridge132 is connected to an ink providing opening 105 of the ink tank 101 bya tube 133. A supply pump 134 for pressurizing and sending the ink ofthe main cartridge 132 and a supply valve 135 for opening and closingthe ink supply passage (i.e., the tube 133) are provided on appropriatepositions of the tube 133 between the main cartridge 132 and the inktank 101.

In the ink providing device including such an ink tank 101, the inkproviding procedure is as follows. When the ink is supplied to the inktank 101, as shown in FIG. 13, an air releasing valve 108 is made openso as to open the air releasing opening 107, that is, open the inside ofthe ink tank 101 to the outside air. Next, the pressing means 131 isdriven to move the plunger 131 a forwards so as to press the film 103 ofthe ink tank 101 against the spring force of the compressed spring 104.In this manner, the inside capacity of the ink tank 101 is decreased.

Thereafter, in this state, the valve 135 is made open, and the supplypump 134 is operated so that the ink in the main cartridge 132 can besent in the pressurized state to the inside of the ink tank 101 via thesupply tube 133. In this manner, a predetermined amount of ink isprovided to the ink tank 101. When the ink supply to the ink tank 101 iscompleted, the operation of the supply pump 134 is stopped, and thevalve 135 is closed to shut the ink supply to the ink tank 101 via thetube 132. In addition, the air releasing valve 108 is closed to shut anair releasing passage of the ink tank 101.

Then, as shown in FIG. 14, the driving of the pressing means 131 isstopped so as to move the plunger 131 a backwards. In this manner, therestoring force of the compressed spring 104 causes the film 103 to moveoutwards, and the negative pressure is thereby generated in the ink tank101.

According to the third embodiment, the negative pressure in the ink tank101 is generated by opening and closing the air releasing opening of theink tank 101, and changing the inside capacity of the ink tank 101.Accordingly, the ink can be supplied to the ink tank 101 withoutincreasing the waste ink produced at the time of the ink supply andwithout degrading the quality of the ink in the main ink cartridge.

Furthermore, as another method of generating the negative pressure inthe ink tank 101, after the ink is provided to the ink tank 101, and theair releasing valve 108 is closed to make the closed state of the inktank 101, the negative pressure can be generated by discharging the inkfrom the ink tank 101 via the head. This method may be applied, but theink discharged from the head is wasted. Accordingly, the above method ofgenerating a negative pressure by changing the capacity of the ink tankis superior to the method of generating a negative pressure bydischarging the ink in that the wasted ink can be decreased.

As another method of generating the negative pressure, after the inktank is closed, the supply pump is driven in reverse so that the ink inthe ink tank can be sent back to the main cartridge. In this method, thewasted ink is not increased, but the ink that flows through the supplytube and the pump is mixed with the ink in the main cartridge.Accordingly, a quality such as deaeration of the ink in the maincartridge is degraded.

Meanwhile, according to the third embodiment of the present invention,the ink tank 101 itself generates the negative pressure as describedabove without discharging the ink of the ink tank from the head.Accordingly, the ink is not wasted. Furthermore, since the ink is notsent back to the main cartridge when generating the negative pressure,the quality of the ink in the main cartridge is not degraded.

Next, a fourth embodiment of the present invention will be describedwith reference to FIGS. 15 and 16. In FIG. 15, the basic structure of anink providing device including an ink tank is shown, and in FIG. 16, theoperation of the ink providing device is shown.

In the forth embodiment, the difference in the pressure head between theink tank 101 and the main cartridge 132 is used instead of the supplypump 134 used in the third embodiment.

With this structure, it is possible to provide the ink to the ink tank101 from the main cartridge 132 by using the difference in the pressurehead. In this case, since the pump is not necessary, the ink providingdevice can be manufactured at a low cost.

In this embodiment, as a method of providing the ink to the subtank fromthe main cartridge, the main cartridge 132 may be made of flexiblematerials so that the pressurized ink can be provided to the subtankfrom the main cartridge by deforming the main cartridge.

Next, a fifth embodiment of the present invention will be described withreference to FIGS. 17 through 19. The basic structure of an inkproviding device according to the fifth embodiment is shown in theelevation view of FIG. 17. FIG. 18 is a plan view of an important partof the ink providing device, and FIG. 19 is a plan view showing theoperation of the ink providing device.

In the fifth embodiment, a displacement member (or a moving member) 109is provided at an ink tank 101. The displacement member 109 can move orrotate, centering the point “a” of FIGS. 18 and 19, in accordance withthe deformation of the film 103. The displacement member 109 is made ofa leaf spring or the like. The spring force of the displacement member109 is set to be weaker than the spring force of a compressed spring 104provided in the ink tank 101. The displacement member 109 is moved inaccordance with the deformation of the film 103, i.e., the increase orthe decrease of the ink in the ink tank 101. Displacement detectionmeans 136 includes a transmission photo sensor for detecting thedisplacement of the displacement member 109 by detecting the existenceor absence of a detection piece 109 a provided at the end of thedisplacement member 109 of the ink tank 101.

With this structure, when the ink in the ink tank 101 is consumed, asshown in FIG. 19, the film 103 is deformed in the inward directionagainst the spring force of the compressed spring 104 provided in theink tank 101. In this state, the negative pressure in the ink tank 101is stronger than the spring force of the compressed spring 104.

Then, as shown in FIG. 19, when the detection piece 109 a of thedisplacement member 109 is detected by the displacement detection means136, a supply pump 136 is operated without opening the air releasingvalve 108 so that the ink in a main cartridge 132 can be provided to theink tank 101 with the inside of the ink tank 101 being shut off from theoutside air. Thereby, the film 103 swells or is deformed outwards, andthe inside capacity of the ink tank is increased to reduce the degree ofthe negative pressure in the ink tank 101. Since the film 103 isdeformed outwards by supplying the ink to the ink tank 101, thedisplacement member 109 is also moved outwards.

When a predetermined amount of ink is supplied to the ink tank 101, asshown in FIG. 18, the detection piece 109 a of the displacement member109 comes to be off (that is, separated from) the displacement detectionmeans 136. From this state, the displacement detection means 136 detectsthat a predetermined amount of ink has been supplied to the ink tank101. Then, a detection signal generated by the displacement detectionmeans 136 causes the operation of the supply pump 134 to be stopped sothat the ink supply to the ink tank 101 can be stopped.

In this case, if the amount of ink that is provided to the ink tank 101exceeds a certain amount, the inside pressure of the ink tank 101becomes positive. Accordingly, when the ink is supplied to the ink tank101 with the ink tank 101 being closed from the outside air, it isnecessary to stop the operation of the supply pump 134 to stop the inksupply to the ink tank 101 before the inside pressure of the ink tank101 changes from a negative pressure to a positive pressure.

By taking this point into account, the setting is made such that thedetection piece 109 a of the displacement member 109 comes to be off thedisplacement detection means 136 before the pressure inside the ink tank101 changes to a positive pressure from a negative pressure. In thismanner, in the state in which the inside pressure of the ink tank 101 isnegative, the operation of the supply pump 134 can be stopped to stopthe ink supply to the ink tank 101.

Accordingly, in the fifth embodiment, even when the inside of the inktank 101 is closed from the outside air, it is possible to repeat theink supply to the ink tank 101 while the negative pressure inside theink tank 101 is kept in an appropriate range.

The displacement detection means 136 may be configured to include twophoto sensors in order to perform finer control. In the case where thedisplacement detection means 136 includes one sensor, when thedisplacement detection means 136 detects the absence of the detectionpiece 109 a of the displacement member 109, the ink supply to the inktank 101 may be started, and when the displacement detection means 136detects the presence of the detection piece 109 a of the displacementmember 109, the ink supply to the ink tank 101 may be stopped. A reversemanner of the above example may be adopted. In this case, the settingmay be made such that when an amount of the ink in the ink tank 101becomes large, the detection piece 109 a of the displacement member 109is detected by the displacement detection means 136.

Furthermore, in this embodiment, since the displacement member 109 canmove or rotate, centering the corner of the ink tank 101 (that is, thecorner functions as the center of the rotation), the displacementdetection means 136 can detect the magnified deformation of the ink tank101 or the film 103. Accordingly, it is possible to detect the timingfor supplying the ink to the ink tank 101 in high accuracy.

According to the second to fifth embodiments, it is possible to supplythe ink to the ink tank 101 both when the inside of the ink tank 101 isopen to the outside air and when the inside of the ink tank 101 isclosed from the outside air. The ink supply to the ink tank 101 with theinside of the ink tank 101 being open to the outside air, and the inksupply to the ink tank 101 with the inside of the ink tank 101 beingclosed from the outside air can be selectively performed for maintainingthe excellent ink supply with high reliability for a long time.

Particularly, the ink is preferably provided to the ink tank 101 withthe inside of the ink tank 101 being open to the outside air fordischarging the gradually accumulated air in the ink tank 101 to theoutside of the ink tank 101. Furthermore, when a large change in atemperature is generated, the negative pressure changes by the expansionand contraction of the air inside the ink tank 101. In this case, afterthe inside of the ink tank 101 is made open to the outside air withoutsupplying the ink to the ink tank 101, the negative pressure generationoperation may be performed to adjust the negative pressure in the inktank 101 so as to maintain the function of the ink tank 101.

By opening the inside of the ink tank 101 to the outside air, theunnecessary air can be discharged to the outside. However, if the insideof the ink tank 101 is made open to the outside air with high frequency,the drying of the inside of the ink tank 101 is promoted. As a result,the ink inside the ink tank 101 can has high viscosity. Accordingly,preferably, the inside of the ink tank 101 is made open with lessfrequency, and the usual ink supply to the ink tank 101 is carried outwith the inside of the ink tank 101 being closed from the outside air.Thus, the ink supply to the ink tank 101 with the inside of the ink tank101 being open to the outside air is preferably performed on apredetermined condition. For example, when the main cartridge 132 isreplaced with new one, when the ink tank 101 has not been used for along time, or when the instruction is provided from a user, the insideof the ink tank 101 may be made open to the outside air.

Next, a sixth embodiment of the present invention will be described withreference to FIGS. 20 through 22. The basic structure of an inkproviding device of the sixth embodiment is shown in an elevation viewof FIG. 20, FIG. 21 is a plan view showing a important part of the inkproviding device, and FIG. 22 is a side view showing an important partof the ink providing device. In this embodiment, a part of adisplacement member 109 is cut and made to stand obliquely so as to forma displacement operation part 109 b, as shown in FIG. 21. With thisstructure, the displacement operation part 109 b is pushed in thedirection indicated by the arrow “A” by an operation part such as alever so that the volume inside an ink tank 101 can be changed.

In other words, the displacement member 109 can be used as pressingmeans for pressing a flexible film 103 of the ink tank 101 against thespring force of a compressed spring 104 in the ink tank 101.Particularly, in the case of the color inkjet printing apparatus, when aplurality of ink tanks 101 are arranged so as to be close to each other,it becomes difficult to directly press the film 103 in the directions ofthe expansion and the contraction of the compressed spring 104. However,with the structure of this embodiment, even if a plurality of ink tanksare arranged so as to be close to each other, the displacement member109 can be moved from the outside-to-inside direction of the ink tank togenerate the negative pressure.

Furthermore, in this embodiment, the displacement member 109 is made ofmaterial such as metal having high thermal conductivity, and a driverintegrated circuit 142 mounted on a connection member (a electricconducting member) 141 such as a FPC (flexible printed circuit) forproviding a driving signal to the inkjet head 120 is made to be incontact with the outside surface of the displacement member 109, asshown in FIG. 22.

In other words, when the ink tank 101 is directly connected to the head120, in many cases, the connection member 141 is disposed on the sidesurface of the ink tank 101. This is because it is impossible to arrangethe connection member 141 at the nozzle surface side where the paperruns. In this case, the driver integrated circuit (driving circuit) 142is mounted on the connection member 141 for the sake of a small mountingarea. However, when the number of nozzles of the inkjet heads increases,and the printing speed becomes high, a substantial amount of heat isgenerated from the driver integrated circuit 142. At this time, it isdifficult to disperse the generated heat because the heads are usuallyarranged so as to be close to each other in the carriage.

For this reason, the metal having high thermal conductivity is used asmaterial for the displacement member 109, and a part of the metaldisplacement member 109 is made to extend to the place where airsufficiently communicates with the outside of the printer. In thismanner, it is possible to easily disperse the heat generated from thedriver integrated circuit 142 via the displacement member 109.

Next, a seventh embodiment of the present invention will be describedwith reference to FIGS. 23 through 25B. The basic structure of an inkproviding device including an ink tank of this embodiment is shown inFIG. 23, and a part of the ink tank is shown in FIGS. 24A and 24B, and apart of another example of the ink tank is shown in FIGS. 25A and 25B.

In this embodiment, reverse flow prevention valve 111 that is reverseflow prevention means for preventing the reverse flow of the ink, i.e.,preventing the ink from flowing to the main cartridge 132 from an inkproviding opening 105, is provided at or near the ink providing opening105 of the ink tank 101, as shown in FIGS. 24A and 24B. This reverseflow prevention means may be made of an elastic member. Alternatively,as shown in FIGS. 25A and 25B, the reverse flow prevention means may bethe reverse flow prevention valve 112 that includes a valve seat 112 a,a ball 112 b for opening and closing the ink providing opening 105, anda spring member 112 c for pressing the ball 112 b to make a closedstate.

A main cartridge 132 that provides the ink to the ink tank 101 isprovided at the level that is below the ink tank 101.

With this arrangement, when a supply pump 134 is operated to send theink in the main cartridge 132 to the ink tank 101 in the pressurizedstate, the reverse flow prevention valve 111 is made open by the inkflow from the main cartridge 132 to the ink tank 101 as shown in FIG.24B, or the ball 112 b is pressed by the ink flow from the maincartridge 132 against the spring force of the spring member 112 c asshown in FIG. 25B so that the reverse flow prevention valve 112 can bemade open. In this manner, the ink providing opening 105 is made open,and the ink can flow into the ink tank 101. On the other hand, when theoperation of the supply pump 134 is stopped, the reverse flow preventionvalve 111 is made closed by the ceasing of the ink flow from the maincartridge 132 as shown in FIG. 24A, or the reverse flow prevention valve112 is made closed by the ceasing of the ink flow from the maincartridge 132 as shown in FIG. 25A so that the ink providing opening 105can be closed.

Accordingly, even when the main cartridge 132 is disposed below the inktank 101, it is possible to prevent the ink in the ink tank 101 fromflowing in reverse to the main cartridge 132. In other words, in orderto dispose the main cartridge 132 below the ink tank 101, the reverseflow prevention means such as valve means for opening and closing theink providing opening 105 are provided at the ink tank 101 forpreventing the ink from flowing in reverse to the main cartridge 132from the ink tank 101.

Meanwhile, in the case where the main cartridge 132 is disposed at thelevel below the level of the ink tank 101, the reverse flow preventionmeans such as the valve means are not provided at the ink providingopening 105 of the ink tank 101, and the ink is provided to the ink tank101 from the main cartridge 132 with the inside of the ink tank 101being open to the outside air, an air releasing valve 108 is first madeopen, and the supply pump 134 is operated to provide the ink of the maincartridge 132 to the ink tank 101. After a predetermined amount of inkis provided to the ink tank 101, the operation of the supply pump 134 isstopped, and the air releasing valve 108 is made closed.

However, in this case, if a reverse flow prevention mechanism such as avalve is not provided at the supply pump 134, the difference in thepressure head between the ink tank 101 and the main cartridge 132 causesthe ink in the ink tank 101 to flow in reverse to the main cartridge 132after the operation of the supply pump 134 is stopped and before the airreleasing valve 108 is closed. In this case, if an air layer exits nearthe ink providing opening 105, the air flows in reverse to the maincartridge 132, and then, the ink flows in reverse to the main cartridge132.

Furthermore, if the air exists at the upstream side of the ink tank 101,e.g., in the tube between the ink tank 101 and the main cartridge 132,when the ink is then provided to the ink tank 101 with the inside of theink tank 101 being open to the outside air, the problem is notgenerated, but when the ink is provided to the ink tank 101 with theinside of the ink tank 101 being closed from the outside air, the airflows into the ink tank 101 together with the ink.

For these reasons, the reverse flow prevention means such as the valveare provided at the ink providing opening 105 of the ink tank 101 toprevent the reverse flow of the ink and prevent the air existing betweenthe ink tank 101 and the main cartridge 132 from coming into the inktank 101.

Next, an eighth embodiment of the present invention will be describedwith reference to FIG. 26. The basic structure of an ink providingdevice including an ink tank 101 according to the eighth embodiment isshown in FIG. 26.

In this embodiment, a protruding part 102 a is formed at the upper partof a case 102. The protruding part 102 a is positioned at the levelhigher than the level of the surface on which an ink providing opening105 is formed. An air extraction space 113 is formed at the protrudingpart 102 a. An air releasing opening 107 is formed above the airextraction space 113. In this structure, the position of the inkproviding opening 105 is lower than the position of the air releasingopening 107. In this example, valve means such as a reverse flowprevention valve are not provided at the ink providing opening 105, andthe main cartridge 132 is disposed at the position lower than theposition of the ink tank 101.

With this structure, when the ink is provided to the ink tank 101 fromthe main cartridge 132 with the inside of the ink tank 101 being open tothe outside air, the air inside the ink tank 101 is discharged to theoutside of the ink tank 101 via the air extraction space 113 and the airreleasing opening 107. At this time, since the position of the inkproviding opening 105 is lower than the position of the air releasingopening 107, it is possible to supply the ink to the ink tank 101 untilthe ink providing opening (ink providing hole) 105 is filled with theink, and even if the air in the ink tank 101 remains in the airextraction space 113 that the air releasing opening 107 faces, it ispossible to realize the state in which the air does not remain at theink providing opening 105.

For example, in the state in which the ink providing opening 105 isfilled with the ink as described above, the operation of the supply pump134 is stopped. In this case, the initial reversing flow from the inkproviding opening 105 contains the only ink. Accordingly, it is possibleto prevent the air from flowing in reverse to the main cartridge 132 byclosing the air releasing opening 107 before the reverse flow comes tocontain the air.

According to the eighth embodiment, the air can be prevented fromflowing in reverse to the main cartridge 132 without providing specificreverse flow prevention means such as the valve means at the inkproviding opening 105.

Next, a ninth embodiment of the present invention will be described withreference to FIGS. 27 and 28. The basic structure of an ink providingdevice including an ink tank 101 of the ninth embodiment is shown inFIG. 27, and FIG. 28 is an enlarged view showing an important part ofthe ink tank 101.

In this embodiment, similarly with the eighth embodiment, a protrudingpart 102 a is provided at the upper part of a case 102 such that theposition of the protruding part 102 a is higher than the surface onwhich an ink providing opening 105 is formed. An air extraction space113 is formed at the protruding part 102 a. Furthermore, an airreleasing opening 107 is formed at the upper part of the air extractionspace 113. In this structure, the position of the ink providing opening105 is lower than the position of the air releasing opening 107. Asshown in FIG. 28, a fluid resistance part such as a throttling part 114is formed at the ink providing opening 105. In this example, valve meanssuch as the reverse flow prevention means are not provided at the inkproviding opening 105, and the position of the main cartridge 132 islower than the position of the ink tank 101.

With this structure, it is possible to prolong the time that is theperiod before the reverse air flow is generated, and to prevent the airfrom flowing in reverse to the main cartridge 132 without providing thespecific reverse flow prevention means such as the valve means.

Next, a tenth embodiment of the present invention will be described withreference to FIG. 29. FIG. 29 shows the basic structure of an inkproviding device including an ink tank 101 according to this embodiment.

In this embodiment, a plurality of detection electrodes (detection pins)for detecting the level of the ink are provided in the ink tank 101. Inthis example, two detection electrodes 115 a and 115 b are provided inthe ink tank 101. The length of the detection electrode 115 a is shorterthan the length of the detection electrode 115 b in terms of the depthdirection. With these lengths, the detection electrode 115 a detects theink at the position near the upper surface of a case 102, and thedetection electrode 115 b detects the ink at the deeper position in theink tank 101.

By using this structure, when the ink is provided to the ink tank 101,the detection electrodes 115 a and 115 b respectively contact with theink, and the impedance between the detection electrode 115 a and thedetection electrode 115 b changes. When the ink is thereby detected, theink supply to the ink tank 101 is stopped.

When the inside of the ink tank 101 is open to the outside air, the inktank 101 takes the shape in which the capacity of the ink tank 101 isthe largest in this state within the range restricted by a pressingmember 121 that is used for generating the negative pressure. At thistime, the ink layer is formed at the lower side of the ink tank 101, andthe air layer is formed at the upper side of the ink tank 101. Then,when a supply pump 134 is operated to provide the ink to the ink tank101 from the main cartridge 132, the air in the ink tank 101 isdischarged from the air releasing opening 107, and the level of the inkis raised. Accordingly, the detection electrode 115 a and the detectionelectrode 115 b respectively come to be immersed in the ink, and theimpedance between the detection electrode 115 a and the detectionelectrode 115 b changes. Therefore, the completion of the ink providing(or the filling of the ink tank 101) can be detected, and the operationof the supply pump 134 is then stopped.

In this example, the detection electrode 115 b is arranged so as to beat the position deeper than the position of the detection electrode 115a. Accordingly, in detecting the level of the ink, it is possible toprevent the detection error. On the other hand, by positioning thedetection electrode 115 a at the upper side of the ink tank 101, it ispossible to increase the amount of the ink at the time the supplying ofink to the ink tank 101 is completed. However, when the position of thedetection electrode 115 a is near the upper surface of the case 102,there is a possibility that foam or bubbles are trapped by the detectionelectrode 115 a, so that the level of the ink cannot be detectedaccurately. The place where the detection electrode 115 a is disposed ispreferably the place where the air tends not to be trapped. Morepreferably, a plurality of detection electrodes are disposed at severalplaces, and when the impedance between any two electrodes of thedisposed detection electrodes changes, it is determined that the inksupplying is completed.

It should be noted that a float on the ink, the permeability of the ink,or reflectance of the ink may be used as means for detecting the levelof the ink to stop the ink supplying.

Next, an eleventh embodiment of the present invention will be describedwith reference to FIG. 30. The basic structure of an ink providingdevice including an ink tank 101 according to this embodiment is shownin FIG. 30.

In this embodiment, a protruding part 102 b is formed at the upper sideof a case 102 of the ink tank 101, and an air extraction space 116 isformed at the protruding part 102 b. An isolation part 102 c integrallyformed with the case 102 is provided at one part of the air extractionspace 116 so as to form a throttling part 117 that is a narrow passageat a part of the air extraction space 116. Furthermore, an air releasingopening 107 that faces the air extraction space 116 is formed as shownin FIG. 30, and a detection electrode 115 a is formed in the throttlingpart 117 of the air extraction space 116. A detection electrode 115 b isalso disposed at the upper side of the ink tank 101, as shown in FIG.30.

In this structure, the ink can more firmly contact with the detectionelectrode 115 a, so that it is possible to prevent the error indetecting the level of the ink.

Next, a twelfth embodiment of the present invention will be describedwith reference to FIGS. 31, 32A and 32B. The basic structure of an inkproviding device including an ink tank 101 according to this embodimentis shown in FIG. 31, and an important part of the ink providing deviceis shown in FIGS. 32A and 32B.

In the twelfth embodiment, an air releasing valve 108 having a housing118 integrally formed on an a case 102 of the ink tank 101 is added tothe ink providing device of the eleventh embodiment. This air releasingvalve 108 includes a valve seat 108 a provided in the housing 118, aball 108 b that can contact with the valve seat 108 a, and a springmember 108 c for pressing the ball 108 b towards the valve seat 108 a,i.e., driving the air releasing valve 108 to be closed.

A valve operation pin 151 is provided outside the air releasing valve108, as shown in FIG. 31. The valve operation pin 151 as driving meansadvances in the air releasing valve 108 to press the ball 108 b in theinward direction against the spring force of the spring member 108 c,thereby driving the air releasing valve 108 to be open.

As shown in FIGS. 32A and 32B, the valve operation pin 151 is providedat a member such as a carriage member 152 for fixing the ink tank 101such that the valve operation pin can move in the carriage member 152relative to the carriage member 152. A spring 153 of the carriage member152 presses the valve operation pin 151 backwards. Furthermore, arestriction member 151 b having a flange is formed on the valveoperation pin 151. The restriction member 151 b restricts an amount thatthe valve operation pin 151 advances in the air releasing valve 108 soas to prevent the advancing amount of the valve operation pin 151 fromexceeding a predetermined amount. The valve operation pin 151 is drivenby a solenoid, a link mechanism, a motor, or the like (not shown).

With this structure, the air releasing valve 108 can be opened andclosed by moving the valve operation pin 151 forwards and backwards.Accordingly, the air releasing operation can be appropriately performed,and the function or quality of the ink tank 101 can be maintained for along time.

The air releasing valve 108 needs to have the tolerance for being firmlyoperated many times in order to repeatedly be opened and closed. Asdescribed above, the spring member 108 c presses the ball 108 b, meaningthat in a normal state, the air releasing valve 108 is closed. Only whenthe ink is provided to the ink tank 101 or when the ink tank 101 isfilled with the ink, the force from the outside is made to act againstthe spring force of the spring member 108 c so as to open the airreleasing valve 108. Accordingly, the structure becomes simple.Furthermore, by only pressing the ball 108 b constituting a sealing partso as to move the ball 108 b by a small length, strict accuracy in thepressing stroke of the valve operation pin 151 is not required becausethe spring member 108 c is provided against the pressing stroke.Accordingly, it is possible to simplify the structure for operating theair releasing valve 108.

In this example, the ink tank 101 is integrally fixed directly on aprinting head 120, so that the ink tank 101 and the printing head 120are fixed together on the carriage (not shown) at a predeterminedposition. Accordingly, the valve operation pin 151 can firmly press andmove the ball 108 b in the inward direction to release the air in theink tank 101.

Since the spring member 153 presses the valve operation pin 151 in thedirection of separating the valve operation pin 151 from the ink tank101, it is possible to securely obtain the normal state in which thevalve operation pin 151 does not interfere with the air releasing valve108. Therefore, with the simple structure, it is possible to firmly openand close the air releasing valve 108. Furthermore, since therestriction part 151 b for restricting the pressed amount of the valveoperation pin 151 is provided on the valve operation pin 151, it ispossible to prevent the air releasing valve 108 from being damaged atthe time of the assembling, and to prevent the ink tank 101 from beingpositioned off a predetermined position on the carriage at the time ofthe assembling.

Next, a thirteenth embodiment of the present invention will be describedwith reference to FIGS. 33 and 34. The basic structure of an inkproviding device including an ink tank 101 according to this embodimentis shown in FIG. 33, and an important part of the ink providing deviceis shown in FIG. 34.

In the thirteenth embodiment, a displacement operation part 109 b of adisplacement member 109 of the ink tank 101 as described in the sixthembodiment is provided. This displacement operation part 109 is operatedby an operation pin 161.

The operation pin 161 is attached on a carriage member 152 or the likefor fixing the ink tank 101 such that the operation pin 161 can advanceand retreat to and from the ink tank 101. A spring 163 presses theoperation pin 161 in the retreating direction of the operation pin 161.A restriction part 161 b having a flange is formed on the operation pin161. The restriction part 161 b restricts an amount that the operationpin 161 advances towards the ink tank 101. In other words, therestriction part 161 prevents the displacement member 109 from beingmoved beyond a predetermined amount by the restricting the advancingamount of the operation pin 161. The operation pin 161 is driven by asolenoid, a link mechanism, a motor, or the like (not shown) Asdescribed above, the operation pin 161 is provided on the carriage suchthat the operation pin 161 can move forwards and backwards. Accordingly,with the simple structure, the operation pin 161 can press thedisplacement operation part 109 b so as to change the inside capacity ofthe ink tank 101 via the displacement member 109 and generate thenegative pressure in the ink tank 101. Since the operation pin 161 ismounted on the carriage or the like that fixes ink tank 101 at thepredetermined position thereon, it is possible to accurately determinethe amount that the displacement member 109 is pressed by the operationpin 161, so that the change in the inside capacity of the ink tank 101can be controlled in high accuracy.

Furthermore, the restriction part 161 b for restricting the pressedamount of the operation pin 161 is provided on the operation pin 161, sothat it is possible to prevent the displacement member 109 from beingdamaged at the time of assembling the printing apparatus, and it ispossible to prevent the ink tank 101 from being off the predeterminedposition on the carriage at the time of assembling the printingapparatus.

Next, a fourteenth embodiment of the present invention will be describedwith reference to FIGS. 35 and 36. The basic structure of an inkproviding device including an ink tank 101 according to this embodimentis shown in FIG. 35, and FIG. 36 is an elevation view of the inkproviding device.

This ink providing device includes a compressed spring 104A, provided inthe ink tank 101, for generating the negative pressure in the ink tank101, and a compressed spring 104B, provided in the ink tank 101, formaintaining the generated negative pressure. In this example, thecompressed spring 104A can be pressed by a pressing part 131 a.

By using two spring members, i.e., the spring member for generating thenegative pressure, and the spring member for maintaining the negativepressure, it is possible to control the initial negative pressuregenerating operation, and the negative pressure maintaining operation,independently of each other. Therefore, the design and the adjustment ofthe structure become easy.

Next, a fifteenth embodiment of the present invention will be describedwith reference to FIGS. 37 and 38. FIG. 37 is a plan view showing thebasic structure of an ink providing device including an ink tank 171according to this embodiment, and FIG. 38 is an elevation view of theink providing device.

In this embodiment, the ink tank 171 includes a case 172 (main body ofthe ink tank 171) made of resin. An isolation wall of the case 172isolates the both sides of the case 172 such that two symmetricalopenings are formed at the both sides, as shown in FIG. 37. In otherwords, two rooms 71A and 71B are defined by the case 172. The ink tank171 further includes a film 173A for sealing the opening of the room171A, and a film 173B for sealing the opening of the room 171B. Further,a compressed spring 174A for pressing the film 173A in the outwarddirection is provided in the room 171A, and a compressed spring 174B forpressing the film 173B in the outward direction is provided in the room171B.

Displacement members 179A and 179B that can move in accordance with thechange in the capacity of the ink tank 171 are provided on the ink tank171. For example, the displacement members 179A and 179B may be rotated,centering the corners of the ink tank 171. Detection pieces 179 a and179 b are provided on the displacement members 179A and 179B,respectively.

In this structure, the ink tank 171 can accommodate two types of ink,e.g., two different colors of ink, so that the size of the printingapparatus can be made smaller.

Next, one example of an inkjet printing apparatus according to thepresent invention will be described with reference to FIG. 39. FIG. 39is a perspective view showing an important part of the inkjet printingapparatus.

This inkjet printing apparatus includes a carriage 213 that is providedin a main body of the apparatus and can move in the main runningdirection. The inkjet printing apparatus further includes a printingmechanism 202 that has an ink cartridge integrally formed on a printinghead such as an inkjet head mounted on the carriage 213.

The printing mechanism 202 includes a main guide rod 211 and an assistguide rod 212 that are laid by being supported by side plates (notshown). The main guide rod 211 and the assist guide rod 212 support thecarriage 213 such that the carriage 213 can move along the guide rods211 and 212, i.e., can move in the main running direction. The printingmechanism 202 further includes a main running mechanism having a mainrunning motor 214 and a timing belt 215.

Ink ejecting holes of the inkjet heads (printing heads) that eject theink of yellow, cyan, magenta, and black are arranged in the directioncrossing (orthogonal to) the main running direction of the carriage 213,and oriented downwards. Ink tanks corresponding to respective colors areattached on the respective printing heads.

At the time of the printing, the printing heads are driven in accordancewith an image signal while the carriage 213 is moved. At this time, theprinting heads eject the ink on standing paper to perform the one-lineprinting. Subsequently, the paper is moved by a predetermined length byan assist running mechanism (sub-running mechanism) including an assistrunning motor 216, and the printing is then performed on the next line.When the printing mechanism 202 receives a printing end signal or asignal indicating that the back end of the paper reaches the printingregion, the printing mechanism 202 stops the printing operation, anddischarges the printed paper.

A recovering device 217 that makes the printing heads recover fromdeteriorated ejecting condition is disposed at the right end side of themoving direction of the carriage 213 off the printing region, as shownin FIG. 39. The recovering device 217 has cap means, sucking means, andcleaning means.

When the carriage 213 waits for the printing, the carriage 213 is movedto the recovering device 217, and the printing heads are capped by thecap means in order to maintain a wet state of the ejecting holes. Inthis manner, it is possible to prevent the deteriorated ink ejectingperformance that is caused by the drying of the ink ejecting holes.Furthermore, by ejecting the ink that is not used for printing from theink ejecting holes in the middle of the printing operation, the inkviscosity of all the ink ejecting holes can be made constant to maintainthe stable ink ejecting performance.

When the ink cartridge is replaced or when the ink ejecting performanceis deteriorated, the ink ejecting holes of the printing heads are cappedby the cap means, and by using a tube, foam as well as the ink adheringto the surface of the ink ejecting holes is suctioned by the suckingmeans to remove the foam and the ink from the ink ejecting holes. Inthis manner, the printing heads can recover from the deterioratedejecting condition. The suctioned ink is discharged to a waste inkreceiving part (not shown) disposed at the lower part of the main body201 of the printing apparatus. The waste ink in the waste ink receivingpart may be absorbed and held by an ink absorbing body in the waste inkreceiving part.

One example of an ink providing device that is applied to this inkjetprinting apparatus shown in FIG. 39 will be described with reference toFIGS. 40 through 43. This ink providing device includes ink tanks 221.FIG. 40 is a plan view showing the entire structure of the ink providingdevice, FIG. 41 is a side view of FIG. 40, FIG. 42 is a plan view of theink tank 221, and FIG. 43 is a side view of FIG. 42.

Four ink tanks 221 corresponding to four colors are mounted on thecarriage 213 in order to obtain a full-color image by ejecting fourcolors. The printing heads located under the ink tanks 221 are connecteddirectly to the ink tanks 221.

The ink tank 221 may be any of the ink tanks described in the aboveembodiments or combination thereof. As one example, each of the inktanks 221 includes a case 102 made of resin, a flexible film 103 forcovering an opening of the case 102, and a compressed spring 104 forpressing the film 103 in the outward direction. An ink providing opening105 having a reverse flow prevention valve 212 is formed on the case102. Further, an ink supply opening 106, and an air releasing opening107 having an air releasing valve 108 are formed on the case 102. An airextraction space 116 is formed in each ink tank 221 at the upper side ofeach ink tank 221. A throttling part 117 that communicates with the airreleasing opening 108 is formed at the air extraction space 116. Adetection electrode 115 a is disposed at the throttling part 117, and adetection electrode 115 b is disposed at the inside surface of the upperwall of the case 102. Furthermore, a displacement member 109 providedoutside the ink tank 221 moves in accordance with the movement of aflexible film 103 corresponding to the change in the capacity or volumeof the ink tank 221. In addition, a displacement operation part 109 b isformed on the displacement member 109. A valve operation pin 151 foropening and closing the air releasing valve 108 of each ink tank 221 ismounted on the carriage 213. An operation pin 161 for pressing thedisplacement operation part 109 b of the displacement member 109 is alsomounted on the carriage 213. The valve operation pin 151 can moveforwards and backwards to and from the air releasing valve 108, and theoperation pin 161 can move forwards and backwards to and from thedisplacement operation part 109 b.

Each ink tank 221 is connected to a main cartridge 232 fixed on the mainbody of the printing apparatus via a tube 233 and a supply pump 234.

Meanwhile, the recovering mechanism 217 provided at the main body of theprinting apparatus has the cap means 241 for capping the printing heads,and a sucking pump (or an evacuation pump) 242 that is the sucking means(or evacuation means). The sucking pump 242 is connected to the capmeans 241 that is located at the position most near the printing region,out of the plural cap means 241, as shown in FIG. 40. The recoveringmechanism 217 further includes a waste ink tank 243 for holding thesucked waste ink, and a wiper 244, provided next to the cap means 241,for wiping the ink, dust, and the like adhering to the nozzle surfacesof the printing heads.

The ink sucking means (in this example, the sucking pump) 242 may beconnected to all of the cap means 241, but in this example, the suckingpump 242 is connected to the cap means located most near the printingregion. In addition, the sucking pump 242 as the ink sucking means mayinclude a tubing pump, a piston pump,, or the like.

The wiping direction of the wiper 244 may be either the moving direction(main running direction) of the carriage 213 or the feeding direction ofthe paper (sub-running direction). In this example, at the time of thewiping, the wiper 244 is raised, and the wiping is performed by themovement of the carriage 213, that is, the main running direction wipingis performed.

Furthermore, a driving actuator 245 is provided at the side of therecovering mechanism 217. The driving actuator 245 has operation pieces145 a and 145 b for moving valve operation pin 151 and an operation pin161 forwards and backwards, respectively. In this example, the operationpin 161 for moving the displacement member 109 is not pressed backwardsby a spring member, and the operation pin 161 is made to advance by oneadvancing and retreating motion of the operation piece 245 b of thedriving actuator 245, and is made to retreat by next one advancing andretreating motion of the operation piece 245 b.

Next, a control unit related to the ink providing in this inkjetprinting apparatus will be described with reference to FIG. 44.

A main control unit 251 controls the entire inkjet printing apparatus,and includes a CPU, a ROM, a RAM, and an I/F (interface). The maincontrol unit 251 receives printing data from a host device (not shown)via a cable or a line, and causes each unit to perform the printingoperation. Furthermore, the main control unit 251 performs control sothat the ink tank 221 can be filled with the ink, or a predeterminedamount of ink can be supplied to the ink tank 221.

In other words, the main control unit 251 drives and controls the mainrunning motor 214 via a motor driver 252 to move the carriage 213 in themain running direction. In addition, the main control unit 251 drivesand controls an assist running motor 216 to move the paper in thesub-running direction. Further, the main control unit 251 causesprinting data or the like to be sent to the head driver 253, and drivesthe pressure generation means of the printing head such as the inkjethead to eject the ink in accordance with the printing data. In thismanner, an image is recorded on the paper. The inkjet head may be apiezoelectric type head having a piezoelectric element used for thepressure generation means, a thermal type head having a heat generationresistance body used for the pressure generation means, or a staticelectric type head having a vibration plate and an electrode.

The main control unit 251 drives and controls a motor 256 of therecovering device 217 via a subsystem driver 255. By using the motor256, a cam mechanism, or the like, the recovering device 217 moves thecap means 241 and the wiper 244 upwards and downwards, starts and stopsthe operation of the sucking pump 242, and moves a carriage lock member(not shown) upwards and downwards.

Furthermore, the main control unit 251 drives and controls the supplypump 134 and a driving actuator 245 via an ink providing driver 257 soas to control the ink supply to the ink tank 221, the airreleasing/shutting of the ink tank 221, and the capacity change of theink tank 221.

The main control unit 251 is connected to the detection electrodes 115 aand 115 b, and receives from an ink remaining amount detection part 258associated with the electrodes 115 a and 115 b an ink remaining amountsignal indicating that the ink providing is completed, or the inkproviding is nearly completed. Further, the main control unit 251 isconnected to the displacement detection means (detection sensor) 136 fordetecting movement of the displacement member 109 of the ink tank 221,and receives a signal from the displacement detection means 136. Inaddition, the main control unit 251 is connected to a temperature sensor259 for detecting a circumambient temperature, and receives a detectedtemperature signal from the temperature sensor 259.

Next, an initial ink providing operation to the ink tank 221 in thisinkjet printing apparatus will be described with reference to FIG. 45.

In FIG. 45, first, the carriage 213 is moved to the side of therecovering device 217, and the ink tank 221 to be filled with the ink ismoved to the place above the cap means 241 connected to the sucking pump242. The motor 256 is driven to move the cap means upwards so that thenozzle surface of the printing head connected to the ink tank 221 cappedby the cap means 241.

Secondly, the pin driving actuator 245 is driven to advance the valveoperation pin 151 so that the air releasing valve 108 of the ink tank221 can be opened. In addition, by the pin driving actuator 245, theoperation pin 161 is made to advance to operate or press thedisplacement operation part 109 b of the displacement member 109 so thatthe displacement member 109 can be moved or rotated. In this manner, thedisplacement member 109 presses the film 103 in the inward direction ofthe ink tank 221 against the spring force of the compressed spring inthe ink tank 221 so that the inside capacity of the ink tank 221 can bereduced.

Thirdly, the supply pump 134 is operated to start the ink providing tothe ink tank 221 from the ink cartridge (the main cartridge 132). Then,by checking a detected signal provided from the ink remaining amountdetection part 258, it is determined whether or not the ink providing tothe ink tank 221 is completed. When it is determined that the inkproviding is completed, the operation of the supply pump 134 is stopped.

Fourthly, the sucking pump 242 is driven to suck the ink from the nozzleof the printing head 254 so that the printing head 254 can be filledwith the ink. Thereafter, the supply pump 134 is again operated tosupply to the ink tank 221 the ink corresponding to the amount reducedby sucking the ink to fill the printing head with the sucked ink so asto fill the ink tank 221 with the ink.

In this state, the ink exudes (leaks) from the nozzle because the insideof the ink tank 221 is open to the outside air. From this state, theoperation of the part of the driving actuator 245 for driving the valveoperation pin 151 is stopped to make the valve operation pin 151retreat. The air releasing valve 108 is thereby closed, that is, the inktank 221 is shut up from the outside air.

Subsequently, the motor 256 is driven to move the cap means 241downwards so as to remove the capping on the printing head. In addition,the wiper 244 is made to move upwards, and the carriage 213 is moved sothat the nozzle surface of the printing head 254 having the filled inkcan be wiped by the wiper 244. In this manner, the meniscus is formed onthe nozzle of the printing head 254, and the ink stops exuding from thenozzle.

Thereafter, the operation piece 145 b of the driving actuator 245 isagain moved forwards and backwards, so that the operation pin 161 ismade to retreat, and the displacement member 109 can move or rotate.Accordingly, the film 103 of the ink tank 221 is pressed by thecompressed spring 104, and the capacity of the ink tank 221 increases,resulting in the negative pressure being generated in the ink tank 221.

The initial ink providing operation is completed by performing theabove-described procedure on all of the ink tanks 221, and the printingbecomes ready to be performed.

Additionally, the negative pressure may be generated before the nozzlesurface is wiped. However, in this case, the meniscus is not formed onthe nozzle, and the negative pressure is generated in the state in whichthe ink that is sucked to the head remains on the nozzle surface, sothat the foam generated at the nozzle tends to be recorded on the papertogether with the ink.

Next, ink providing control will be described with reference to FIG. 46.

First, based on a detected signal provided from the ink remaining amountdetection part 258, or a signal provided from the displacement sensor136, it is determined whether or not it becomes necessary to supply theink to the ink tank 221. When the ink supply becomes necessary, it isdetermined whether or not the ink cartridge (the main ink cartridge) 132has been replaced. When it is determined that the ink cartridge 132 hasnot been replaced, it is determined whether or not the ink cartridge 132has not been used for a long time. If it is determined that the inkcartridge 132 was used recently, the ink is supplied to the ink 221 withthe inside of the ink tank 211 being closed from the outside air. Atthis time, the ink is supplied to the ink tank 211 while the operationpin 151 of the driving actuator 245 is not operated so as to keep theair releasing pin 108 closed.

On the other hand, when the ink supply becomes necessary, and the inkcartridge 132 has been replaced with new one, or the ink cartridge 132has not been used for a long time, the ink is supplied to the ink tank211 with the inside of the ink tank 211 being open to the outside air.At this time, the operation pin 151 of the driving actuator 245 isoperated so as to keep the air releasing valve 108 open.

In addition, even when the ink supply is not necessary, if based on adetected signal provided from the temperature sensor 259, it isdetermined that the temperature detected by the temperature sensor 259continue to take a value more than a set value for a predeterminedperiod, the operation pin 151 of the driving actuator 245 opens the airreleasing valve 108, and the inside of the ink tank 211 is temporarilyopened to the outside air.

In such a manner, the ink providing to the ink tank 211 with the insideof the ink tank 211 being closed from the outside air, and the inkproviding to the ink tank 211 with the inside of the ink tank 211 beingopen to the outside air are selectively performed, so that the ink canbe provided to the ink tank 211 for a long time without reducing the inkquality.

Next, a specific embodiment of the present invention will be describedwith reference to FIGS. 47 through 49. An inkjet printing apparatus, anink tank, and an ink providing device in this embodiment are basicallythe same as those shown in FIGS. 39 through 43. A case 302 of an inktank 301 is made of polyethylene resin, and one side of the case 301 issealed by a flexible film 303. The inside capacity of the ink tank 301is about 7 cc. The inside surface of the film 303 is formed bypolyethylene having low density, and the outside surface of the film 303is formed by nylon having the thickness of 80 μm. The inside surface andthe outside surface of the film 303 are coupled to each other by heatmelting. A compressed spring 304 is provided in the case 302 of the inktank 301. In this example, the spring 304 is a swirl spring, and whenthe length of the compressed spring 304 changes by 6 mm, a spring forceof about 20 to 50 gf is generated.

As described in FIG. 47, metal pins 315 a and 315 b that detects thelevel of the ink are provided at the upper surface of the ink tank 301.An air releasing opening 307 that includes a penetrating opening havingthe diameter of about 2 mm is formed at the upper side of the case 302of the ink tank 301. An air releasing valve 308 is provided at the airreleasing opening 307. A part of the air releasing valve 308 is pressedby a spring provided at the air releasing valve 308 so as to be closedin a normal state. In addition, an ink providing opening 305 having adiameter of about 0.5 mm is formed at the upper part of the case 302 ofthe ink tank 301. A tube 333 having the inside diameter of 1 mm isconnected to the ink providing opening 305. The other end of the tube333 is connected to a main cartridge 332 via a piston pump 334.

As one example, the main cartridge 332 is a box-shaped cartridge coveredwith an aluminum film by vapor deposition. A leaf spring 309 having thethickness of 0.15 mm that is a displacement member 309 is formed on theoutside surface of the film 203 of the ink tank 301. The displacementmember 309 may be caulked and attached on the polyethylene case 303 byheat. This leaf spring is bent inwards so as to press the film 303towards the inside of the ink tank 301 at the force of about 5 to 10 gfif the swirl spring 304 does not exist in the ink tank 301.

Furthermore, a detection piece 309 a is provided at a free end of theleaf spring 309, and a photo sensor 336 is provided as displacementdetection means for detecting the movement of the detection piece 309 aof the leaf spring 309. An ink supply opening 306 is provided at thebottom surface of the ink tank 301, and is connected to the printinghead in practical usage.

In this structure, the experiment was performed as follows. A pressuresensor for evaluating the ink tank 301 was provided at the ink supplyopening 306 via a fluid resistance element that provides a fluidresistance value substantially equal to a fluid resistance value of theprinting head.

In this experiment, the ink providing operation was carried out, and thesampling was performed so as to obtain the evaluation of the negativepressure in the ink tank 301. First, the operation pin 351 was made toadvance, and the air releasing valve 308 was thereby opened. Then, inthis state, the leaf spring 309 was moved by about 1 mm toward theinside of the ink tank 301 so as to press the film 303 toward the insideof the ink tank 301. As a result, the capacity of the ink tank 301 wasreduced.

Secondly, the piston pump 334 was operated so as to provide the ink tothe ink tank 301 until the impedance between the metal pins 315 a and315 b functioning as the detection electrodes became low. When the inktank 301 was filled with the ink, the pressure inside the ink tank 301was measured. This measured pressure was a positive pressure of about 40mmAq. Next, the operation pin that was pressing the air releasing valve308 was moved backwards so as to close the inside of the ink tank 301from the outside air. Thereafter, the pressing on the film 303 by theleaf spring 309 as the displacement member was released. In this state,the pressure in the ink tank 301 was measured. The measured pressure wasa negative pressure of −20 mmAq.

Next, when the ink was discharged from the ink tank 301, the degree ofthe negative pressure in the ink tank 301 gradually increased as thedischarged amount of the ink increased. When the amount of thedischarged ink reached about 3.5 cc, the negative pressure became −100mmAq. At this time, the film 303 completely deformed in the insidedirection of the ink tank 301, and the free end of the leaf spring 309contacted with the case 302, similarly with the case shown in FIG. 19.

Then, the air releasing valve 308 was opened again, and the ink wassupplied to the ink tank 301 in the same manner as that of the initialink providing. As a result of this, the ink amount of about 3.5 cc wassupplied to the ink tank 301, and the negative pressure in the ink tank301 became about −20 mmAq again.

Thereafter, the air releasing valve 308 was closed, the supply pump 334was operated, and the ink was again discharged from the ink tank 301until the negative pressure in the ink tank 301 reached the −100 mmAq.The ink supply was stopped by detecting the movement or deformation ofthe leaf spring 309 based on the output from the photo sensor 336. Themovement of the leaf spring was detected by using the end part of theleaf spring 309, so that the amount of the movement of the leaf spring309 could be magnified for the detection, resulting in the accuratedetection. Therefore, with this accuracy, the ink supply to the ink tank301 could be stopped at the negative pressure of −20 mmAq.

In the specific embodiment, additional experiment was carried out. Theink tank 301 used in the above experiment was connected to the printinghead, and mounted on the carriage in the printing apparatus. In thisexperiment, the diameter of the ink providing opening was changed to be2 mm to 5 mm, and with this diameter, the initial ink providing wascarried out. However, when the operation of the piston pump 334 wasstopped, and the air releasing valve 308 was closed, the air flowed inreverse, resulting in the air entering the ink providing tube 333. Theprinting evaluation was repeated until the ink tank 301 became vacant,and again, the ink tank 301 was filled with the ink while the inside ofthe ink tank 301 was closed from the outside air. Then, when theprinting test was performed, good printing quality was obtained.

However, this printing apparatus was placed where a temperature washigh, and when the same printing test was carried out at this place, anabnormal image was recorded. The air that entered inside of the ink tank301 at the time of the ink providing to the ink tank 301 is consideredto be the cause of this. Then, the negative pressure generatingoperation was performed again by opening the inside of the ink tank 301,and in this state, the normal printing quality was obtained.Furthermore, the reverse flow prevention valve 112 was provided at theink providing opening 305, and when the printing test was carried out inthis state, the reverse flow was not generated in the ink providing tube333, and the stable printing quality was obtained.

In the above-described embodiments, the ink tank that holds the ink isused as a liquid tank, but a liquid tank used for the printing head thatejects liquid resist, a DNA sample, or other type of liquid may beapplied to the embodiments of the present invention.

As described above, according to the ink tank related to the presentinvention, the negative pressure is generated inside the liquid tank(the ink tank) by changing the inside capacity of the ink tank, so thatwith the simple structure, it is possible to adjust the negativepressure without increasing unnecessary liquid (ink) consumption.

According to the ink tank related to the present invention, the liquidtank includes the air releasing opening that can be closed and opened sothat the inside of the liquid tank can be closed and opened to theoutside air. The negative pressure can be generated in the liquid tankby opening and closing the air releasing opening, and changing thecapacity of the liquid tank. Accordingly, with the simple structure, itis possible to adjust the negative pressure in the liquid tank withoutincreasing the unnecessary liquid consumption. Furthermore, with thesimple structure, the negative pressure can be generated, and the insideof the liquid tank can be opened to the outside air, so that it ispossible to provide the liquid having reliable quality for a long time.In addition, since the air releasing valve that can be kept closed bythe spring member is installed at the air releasing opening of theliquid tank, it is possible to close and open the inside of the ink tank(liquid tank) to the outside air with the simple structure.

Furthermore, according to the liquid tanks of the above-describedembodiments, the liquid (ink) can be supplied to the liquid tank via theliquid providing opening (ink providing opening) from the outside of theliquid tank; In the case of the liquid tank having the air releasingopening, the liquid providing opening is formed at the position lowerthan the position of the air releasing opening, so that the air can beprevented from flowing in reverse to the main cartridge, and theprinting quality is not deteriorated. In addition, since the reverseflow prevention means for preventing the liquid from flowing in reversefrom the liquid providing opening to the main cartridge, e.g., the valvemeans for preventing the liquid from flowing in the opposite direction,and/or the flow resistance body that produces large flow resistance isprovided, it is possible to prevent the deterioration of the printingquality or the liquid quality caused by the flowing air in the reversedirection.

Further, the pressing means for pressing the liquid tank from theoutside is provided, so that it is possible to generate the negativepressure with the simple structure. The displacement member that movesin accordance with the change of the capacity of the liquid tank isprovided, so that it is possible to easily detect the capacity of theliquid tank. Furthermore, the movement of the displacement member islarger than the deforming of the liquid tank indicating the capacitychange of the liquid tank, so that the detection accuracy can beimproved. In addition, since the displacement member may has the memberthat changes the capacity of the liquid tank, it is possible to generatethe negative pressure in the liquid tank with the simpler structure. Thedisplacement member may be made of the material having the high thermalconductivity, so that it is possible to easily disperse the heatgenerated at the head driving circuit.

Furthermore, by installing at least two detection electrodes extendingto the depths that are different from each other at the inside upperpart of the liquid tank, it is possible to easily detect the amount ofthe liquid in the liquid tank. In the case of the liquid tank having theair releasing opening and the liquid providing opening, one of thedetection electrodes is installed at the air extraction space directlycommunicating with the air releasing opening, so that the detectionaccuracy in detecting the level of the liquid in the liquid tank can beimproved.

Furthermore, the spring member for generating the negative pressure, andthe spring member for maintaining the negative pressure may be installedin the liquid tank, so that it becomes easy to adjust the negativepressure in the liquid tank. The inside of the liquid tank may bedivided into two rooms, and two type of liquid may be accommodated inthe two rooms, respectively, so that the space can be saved.

Since the liquid providing devices (ink providing devices) of theabove-described embodiments have the liquid tank related to the presentinvention, it is possible to provide the liquid having the reliablequality for a long time. The liquid providing device may include liquidproviding means for supplying the liquid to the liquid tank by using thedifference in the pressure head, so that it is possible to provide theliquid to the liquid tank with the simple structure. Furthermore, thedriving member that can move to cause the change in the capacity of theliquid tank may be provided on the member that fixes the liquid tank, sothat it is possible to firmly change the capacity of the liquid tank.Further, the restriction member such as the restriction part 161 b ofFIG. 34 that restricts the amount of the movement of this driving memberis provided, so that the varying amount of the capacity of the liquidtank can be kept in a predetermined range. The driving member such asthe operation pin 161 of FIG. 34 may be provided such that a gap existsbetween the liquid tank and the driving member, and the spring such asthe spring 163 of FIG. 34 may be provided for maintaining this gap inorder to prevent the operation error.

According to the embodiments of the present invention, the liquidproviding device may include the liquid providing means for selectingeither the liquid providing operation in which the liquid is provided tothe liquid tank with the inside of the liquid tank being open to theoutside air, or the liquid providing operation in which the liquid isprovided to the liquid tank with the inside of the liquid tank beingclosed from the outside air. Accordingly, it is possible to realize thestable liquid quality without reducing the liquid quality for a longtime.

According to the embodiments of the present invention, the liquidproviding device may include the opening/closing means for opening theinside of the liquid tank in accordance with the surroundingtemperature. Accordingly, it is possible to realize the stable liquidquality without reducing the quality of the liquid for a long time.

According to the liquid providing devices of the above-describedembodiments, the opening/closing driving member that can move to openand close the air releasing opening of the liquid tank is provided onthe member for fixing the liquid tank. Accordingly, it is possible tofirmly open the inside of the liquid tank to the outside air. Inaddition to that, the restriction member such as the restriction member151 b of FIG. 32A for restricting the movement amount of theopening/closing member is provided, so that the opening degree of theair releasing opening can be kept constant. Furthermore, theopening/closing driving means such as the operation pin 151 of FIG. 32Amay be provided such that a gap exists between the liquid tank and theopening/closing driving member, and the spring member such as the spring153 of FIG. 32A for maintaining this gap may be provided in order toprevent the operation error.

The inkjet printing apparatus according to the present invention mayinclude the liquid tank and/or the liquid providing device (inkproviding device) related to the present invention. Accordingly, theinkjet printing apparatus can stably perform the printing having thehigh quality. In addition, the inkjet printing apparatus may have thewiping means for wiping the nozzle surface of the printing head beforethe negative pressure is generated in the liquid tank. Accordingly, itis possible to stably provide the ink to the head in this inkjetprinting apparatus.

According to the present invention, the liquid tank may be formedintegrally with the inkjet head that ejects the ink. Accordingly, withthe simple structure, the ink can be stably supplied to the inkjet headwhile the liquid tank can hold the ink having the negative pressure.

This patent application is based on Japanese priority patent applicationNos. 2002-030232 and 2002-040038 filed on Feb. 7, 2002 and Feb. 18,2002, respectively, the entire contents of which are hereby incorporatedby reference.

1. A liquid tank that holds liquid to be used by a printing apparatus,having a structure in which a capacity of the liquid tank is changed soas to generate a negative pressure in the liquid tank.
 2. The liquidtank according to claim 1, comprising an air releasing opening that isopened and closed so that an inside of the liquid tank is opened andclosed to outside air, wherein a negative pressure is generated in theliquid tank by opening and closing the air releasing opening, and bychanging the capacity of the liquid tank.
 3. The liquid tank accordingto claim 2, further comprising an air releasing valve, provided at theair releasing opening, for keeping the air releasing opening closed byusing a spring member.
 4. The liquid tank according to claim 1 or 2,further comprising a liquid providing opening used for providing liquidto an inside of the liquid tank from outside the liquid tank.
 5. Theliquid tank according to claim 2, further comprising a liquid providingopening used for providing liquid to the inside of the liquid tank fromoutside the liquid tank, wherein a position of the liquid providingopening is lower than a position of the air releasing opening.
 6. Theliquid tank according to claim 4, further comprising reverse flowprevention means for preventing liquid from flowing in reverse from theliquid providing opening.
 7. The liquid tank according to claim 6,wherein the reverse flow prevention means include valve means forpreventing liquid from flowing in reverse from the liquid providingopening, or a fluid resistance part that produces large fluidresistance.
 8. The liquid tank according to claim 1 or 2, furthercomprising pressing means for pressing the liquid tank from outside theliquid tank.
 9. The liquid tank according to claim 1 or 2, furthercomprising a displacement member that moves in accordance with change ofthe capacity of the liquid tank.
 10. The liquid tank according to claim9, wherein an amount of movement of the displacement member is largerthan an amount of deformation of the liquid tank that indicates thechange of the capacity of the liquid tank.
 11. The liquid tank accordingto claim 9, wherein liquid providing to the liquid tank is controlledbased on a position of the displacement member.
 12. The liquid tankaccording to claim 9, wherein the displacement member has a function ofchanging the capacity of the liquid tank.
 13. The liquid tank accordingto claim 9, wherein the displacement member is made of a material havinghigh thermal conductivity.
 14. The liquid tank according to claim 4,further comprising at least two detection electrodes that are providedat an upper part of an inside of the liquid tank, extend to respectivedifferent depths of the liquid tank, and detect a level of liquid in theliquid tank.
 15. The liquid tank according to claim 4, furthercomprising: a liquid providing opening used for providing liquid to theinside of the liquid tank from outside the liquid tank; at least twodetection electrodes, provided at an upper part of the inside of theliquid tank, for detecting a level of liquid inside the liquid tank; andan air extraction space that communicates with the air releasingopening, wherein one of the detection electrodes is provided at the airextraction space.
 16. The liquid tank according to claim 4, furthercomprising a valve that is provided at the liquid providing opening andis opened and closed in accordance with a pressure inside the liquidtank.
 17. The liquid tank according to claim 1 or 2, further comprising:a spring member, provided inside the liquid tank, for generating anegative pressure inside the liquid tank; and a spring member, providedinside the liquid tank, for maintaining a negative pressure inside theliquid tank.
 18. The liquid tank according to claim 4, wherein liquidproviding to the liquid tank is stopped after the liquid providingopening is filled with the liquid.
 19. The liquid tank according toclaim 1 or 2, comprising a part that divides an inside of the liquidtank into two rooms and isolates the rooms from each other so that oneof the rooms holds one liquid, and the other of the rooms holds anotherliquid.
 20. A liquid providing device, comprising the liquid tankdescribed in claim 1 or 2, wherein the liquid providing device providesliquid to an inside of the liquid tank from outside the liquid tank, andsupplies liquid to a printing head of the printing apparatus from theliquid tank.
 21. The liquid providing device according to claim 20,further comprising liquid providing means for providing liquid to theinside of the liquid tank by using difference in a pressure head. 22.The liquid providing device according to claim 20, further comprising adriving member that is provided on a member for fixing the liquid tankthereon and moves so as to change the capacity of the liquid tank.
 23. Aliquid providing device, comprising the liquid tank described in claim15, wherein the liquid tank further comprising at least one throttlingpart that is formed by making a part of the air extraction space narrow,and said one of the detection electrodes is provided at the throttlingpart.
 24. The liquid providing device according to claim 22, furthercomprising a restriction member for restricting an amount of movement ofthe driving member.
 25. The liquid providing device according to claim22, wherein the driving member is provided on the member for fixing theliquid tank such that a gap exists between the liquid tank and thedriving member, and the liquid providing device includes a spring memberfor maintaining the gap.
 26. A liquid providing device, comprising theliquid tank described in claim 4, wherein the liquid providing deviceprovides liquid to the inside of the liquid tank from outside the liquidtank, and supplies liquid to a printing head of the printing apparatusfrom the liquid tank, wherein the liquid providing device includesliquid providing means for providing liquid to the inside of the liquidtank by selecting either a state where the inside of the liquid tank isopened to outside air or a state where the inside of the liquid tank isclosed from outside air.
 27. A liquid providing device, comprising theliquid tank described in claim 2, wherein the liquid providing deviceprovides liquid to the inside of the liquid tank from outside the liquidtank, and supplies liquid to a printing head of the printing apparatusfrom the liquid tank, wherein the liquid providing device includesopening/closing means for opening the air releasing opening of theliquid tank in accordance with a surrounding temperature.
 28. A liquidproviding device, comprising the liquid tank described in claim 2,wherein the liquid providing device provides liquid to the inside of theliquid tank from outside the liquid tank, and supplies liquid to aprinting head of the printing apparatus from the liquid tank, whereinthe liquid providing device includes an opening/closing driving memberthat is provided on a member for fixing the liquid tank and moves so asto open and close the air releasing opening of the liquid tank.
 29. Theliquid providing device according to claim 27 or 28, further comprisinga restriction member for restricting an amount of movement of theopening/closing means that move so as to open and close the airreleasing opening, or further comprising a restriction member forrestricting an amount of movement of the opening/closing driving member.30. The liquid providing device according to claim 29, wherein theopening/closing means or the opening/closing driving member are providedon a member for fixing the liquid tank such that a gap exists betweenthe liquid tank and the opening/closing means or between the liquid tankand the opening/closing driving member, and the liquid providing devicefurther comprises a spring member for maintaining the gap.
 31. An inkjetprinting apparatus having an inkjet head, comprising the liquid tankdescribed in claim 1, wherein the liquid is ink, and the inkjet printingapparatus supplies ink to the inkjet head from the liquid tank.
 32. Aninkjet printing apparatus having an inkjet head, comprising the liquidproviding device described in any one of claims 20, 26, 27, and 28,wherein the liquid is ink, and the inkjet printing apparatus uses theliquid providing device to supply ink to the inkjet head from the liquidtank.
 33. The inkjet printing apparatus according to claim 31, furthercomprising means for wiping a nozzle surface of the inkjet head beforethe negative pressure is generated inside the liquid tank.
 34. An inkjetprinting apparatus having an inkjet head, comprising the liquidproviding device described in claim 26, wherein the liquid is ink, andthe inkjet printing apparatus uses the liquid providing device to supplyink to the inkjet head from the liquid tank, and the inkjet printingapparatus further comprises means for wiping a nozzle surface of theinkjet head before the negative pressure is generated inside the liquidtank.
 35. An ink cartridge comprising: an inkjet head for ejecting ink;and the liquid tank described in claim 1, wherein liquid is ink, and theinkjet head is integrally formed on the liquid tank.
 36. A pressureadjustment mechanism for an inkjet head device, comprising: a head thatejects ink; a carriage that mounts the head thereon and moves; a subtankthat is mounted on the carriage, temporarily holds ink provided from acartridge, and provides the temporarily held ink to the head; a leverthat is moved to adjust a pressure inside the subtank; and driving meansfor moving the lever selectively to a first position of the lever or asecond position of the lever, wherein the subtank includes pressureadjustment means that have air releasing control means and negativepressure control means, the air releasing control means are provided ona side wall of the subtank, enable an inside of the subtank to be openedto outside air, and enable the inside of the subtank to be closed fromoutside air, and the negative pressure control means generate a negativepressure inside the subtank, the lever acts on the pressure adjustmentmeans at the first position of the lever when the carriage is at asecond position of the carriage, and the acting on the pressureadjustment means by the lever is released at the second position of thelever, the driving means include a cam that acts on the lever so as tomove the lever, and means for rotating the cam, and when the carriage isat a first position of the carriage where the lever does not act on thepressure adjustment means even if the lever is moved to the firstposition of the lever, the lever is moved by the driving means to thefirst position of the lever, and the carriage is moved to the secondposition of the carriage with the lever being at the first position ofthe lever to perform air releasing control for the subtank and negativepressure control for the subtank.
 37. The pressure adjustment mechanismaccording to claim 36, further comprising: a plurality of subtanks thatare mounted on the carriage, have a substantially same structure as thatof said subtank, and hold ink whose types are different from each other;a plurality of levers that have a substantially same structure as thatof said lever; and a plurality of pressure adjustment means that arerespectively provided on the plurality of subtanks, and have asubstantially same structure as that of said pressure adjustment means,wherein each of the plurality of pressure adjustment means receiveaction applied by one of the plurality of levers.
 38. The pressureadjustment mechanism according to claim 36, wherein the pressureadjustment means include an air releasing pin that enables an airreleasing opening formed on the subtank to be opened and closed so as toperform the air releasing control, the negative pressure means include anegative pressure pin that moves a part of a wall constituting thesubtank so as to control a pressure inside the subtank to be a desirednegative pressure, the lever presses the air releasing pin and thenegative pressure pin at the first position of the lever when thecarriage is at the second position of the carriage, and the lever isseparated from the air releasing pin and the negative pressure pin atthe second position of the lever, and the air releasing pin is separatedfrom the negative pressure pin in a vertical direction.
 39. The pressureadjustment mechanism according to claim 36, wherein when the lever actson the pressure adjustment means, and receives a reaction force that isgenerated from the pressure adjustment means and that causes a stressacting on the lever in a direction of releasing the acting by the leveron the pressure adjustment means, the stress received by the lever actson the cam towards a center axis of a rotational shaft of the cam so asto restrain movement of the lever caused by the stress.
 40. The pressureadjustment mechanism according to claim 37, wherein when a series ofmovements of one of the plurality of levers successively orsimultaneously causes some of the plurality of pressure adjustment meansto function, ink is provided to some of the plurality of subtankscorresponding to the some of the plurality of pressure adjustment means.41. An inkjet printer comprising the pressure adjustment mechanismdescribed in claim 36, wherein the inkjet printer provides ink to aninside of the subtank while the inkjet printer uses the pressureadjustment mechanism so as to adjust a pressure in the subtank.